## String Utility Functions

String Utility Functions — various string-related functions.

## Synopsis

    #include <glib.h>
    #include <glib/gprintf.h>

    gchar*      g_strdup                        (const gchar *str);
    gchar*      g_strndup                       (const gchar *str,
                                                 gsize n);
    gchar**     g_strdupv                       (gchar **str_array);
    gchar*      g_strnfill                      (gsize length,
                                                 gchar fill_char);
    gchar*      g_stpcpy                        (gchar *dest,
                                                 const char *src);
    gchar*      g_strstr_len                    (const gchar *haystack,
                                                 gssize haystack_len,
                                                 const gchar *needle);
    gchar*      g_strrstr                       (const gchar *haystack,
                                                 const gchar *needle);
    gchar*      g_strrstr_len                   (const gchar *haystack,
                                                 gssize haystack_len,
                                                 const gchar *needle);
    gboolean    g_str_has_prefix                (const gchar *str,
                                                 const gchar *prefix);
    gboolean    g_str_has_suffix                (const gchar *str,
                                                 const gchar *suffix);

    gsize       g_strlcpy                       (gchar *dest,
                                                 const gchar *src,
                                                 gsize dest_size);
    gsize       g_strlcat                       (gchar *dest,
                                                 const gchar *src,
                                                 gsize dest_size);

    gchar*      g_strdup_printf                 (const gchar *format,
                                                 ...);
    gchar*      g_strdup_vprintf                (const gchar *format,
                                                 va_list args);
    gint        g_printf                        (gchar const *format,
                                                 ...);
    gint        g_vprintf                       (gchar const *format,
                                                 va_list args);
    gint        g_fprintf                       (FILE *file,
                                                 gchar const *format,
                                                 ...);
    gint        g_vfprintf                      (FILE *file,
                                                 gchar const *format,
                                                 va_list args);
    gint        g_sprintf                       (gchar *string,
                                                 gchar const *format,
                                                 ...);
    gint        g_vsprintf                      (gchar *string,
                                                 gchar const *format,
                                                 va_list args);
    gint        g_snprintf                      (gchar *string,
                                                 gulong n,
                                                 gchar const *format,
                                                 ...);
    gint        g_vsnprintf                     (gchar *string,
                                                 gulong n,
                                                 gchar const *format,
                                                 va_list args);
    gint        g_vasprintf                     (gchar **string,
                                                 gchar const *format,
                                                 va_list args);
    gsize       g_printf_string_upper_bound     (const gchar *format,
                                                 va_list args);

    gboolean    g_ascii_isalnum                 (gchar c);
    gboolean    g_ascii_isalpha                 (gchar c);
    gboolean    g_ascii_iscntrl                 (gchar c);
    gboolean    g_ascii_isdigit                 (gchar c);
    gboolean    g_ascii_isgraph                 (gchar c);
    gboolean    g_ascii_islower                 (gchar c);
    gboolean    g_ascii_isprint                 (gchar c);
    gboolean    g_ascii_ispunct                 (gchar c);
    gboolean    g_ascii_isspace                 (gchar c);
    gboolean    g_ascii_isupper                 (gchar c);
    gboolean    g_ascii_isxdigit                (gchar c);

    gint        g_ascii_digit_value             (gchar c);
    gint        g_ascii_xdigit_value            (gchar c);

    gint        g_ascii_strcasecmp              (const gchar *s1,
                                                 const gchar *s2);
    gint        g_ascii_strncasecmp             (const gchar *s1,
                                                 const gchar *s2,
                                                 gsize n);

    gchar*      g_ascii_strup                   (const gchar *str,
                                                 gssize len);
    gchar*      g_ascii_strdown                 (const gchar *str,
                                                 gssize len);

    gchar       g_ascii_tolower                 (gchar c);
    gchar       g_ascii_toupper                 (gchar c);

    GString*    g_string_ascii_up               (GString *string);
    GString*    g_string_ascii_down             (GString *string);

    gchar*      g_strup                         (gchar *string);
    gchar*      g_strdown                       (gchar *string);

    gint        g_strcasecmp                    (const gchar *s1,
                                                 const gchar *s2);
    gint        g_strncasecmp                   (const gchar *s1,
                                                 const gchar *s2,
                                                 guint n);

    gchar*      g_strreverse                    (gchar *string);

    guint64     g_ascii_strtoull                (const gchar *nptr,
                                                 gchar **endptr,
                                                 guint base);
    #define     G_ASCII_DTOSTR_BUF_SIZE
    gdouble     g_ascii_strtod                  (const gchar *nptr,
                                                 gchar **endptr);
    gchar*      g_ascii_dtostr                  (gchar *buffer,
                                                 gint buf_len,
                                                 gdouble d);
    gchar*      g_ascii_formatd                 (gchar *buffer,
                                                 gint buf_len,
                                                 const gchar *format,
                                                 gdouble d);
    gdouble     g_strtod                        (const gchar *nptr,
                                                 gchar **endptr);

    gchar*      g_strchug                       (gchar *string);
    gchar*      g_strchomp                      (gchar *string);
    #define     g_strstrip                      ( string )

    gchar*      g_strdelimit                    (gchar *string,
                                                 const gchar *delimiters,
                                                 gchar new_delimiter);
    #define     G_STR_DELIMITERS
    gchar*      g_strescape                     (const gchar *source,
                                                 const gchar *exceptions);
    gchar*      g_strcompress                   (const gchar *source);
    gchar*      g_strcanon                      (gchar *string,
                                                 const gchar *valid_chars,
                                                 gchar substitutor);
    gchar**     g_strsplit                      (const gchar *string,
                                                 const gchar *delimiter,
                                                 gint max_tokens);
    gchar**     g_strsplit_set                  (const gchar *string,
                                                 const gchar *delimiters,
                                                 gint max_tokens);
    void        g_strfreev                      (gchar **str_array);
    gchar*      g_strconcat                     (const gchar *string1,
                                                 ...);
    gchar*      g_strjoin                       (const gchar *separator,
                                                 ...);
    gchar*      g_strjoinv                      (const gchar *separator,
                                                 gchar **str_array);
    guint       g_strv_length                   (gchar **str_array);

    const gchar* g_strerror                     (gint errnum);
    const gchar* g_strsignal                    (gint signum);

## Description

This section describes a number of utility functions for creating, duplicating, and manipulating strings.

Note that the functions `g_printf()`, `g_fprintf()`, `g_sprintf()`, `g_snprintf()`, `g_vprintf()`, `g_vfprintf()`, `g_vsprintf()` and `g_vsnprintf()` are declared in the header `gprintf.h` which is not included in `glib.h` (otherwise using `glib.h` would drag in `stdio.h`), so you'll have to explicitly include `<glib/gprintf.h>` in order to use the GLib `printf()` functions.

While you may use the `printf()` functions to format UTF-8 strings, notice that the precision of a `%Ns` parameter is interpreted as the number of bytes, not characters to print. On top of that, the GNU libc implementation of the `printf()` functions has the "feature" that it checks that the string given for the `%Ns` parameter consists of a whole number of characters in the current encoding. So, unless you are sure you are always going to be in an UTF-8 locale or your know your text is restricted to ASCII, avoid using `%Ns`. If your intention is to format strings for a certain number of columns, then `%Ns` is not a correct solution anyway, since it fails to take wide characters (see `g_unichar_iswide()`) into account.

## Details

### g_strdup ()

    gchar*      g_strdup                        (const gchar *str);

Duplicates a string. If `str` is `NULL` it returns `NULL`. The returned string should be freed when no longer needed.

`str` : | the string to duplicate.
Returns : | a newly-allocated copy of `str`.

### g_strndup ()

    gchar*      g_strndup                       (const gchar *str,
                                                 gsize n);

Duplicates the first `n` characters of a string, returning a newly-allocated buffer `n` + 1 characters long which will always be nul-terminated. If `str` is less than `n` characters long the buffer is padded with nuls. If `str` is `NULL` it returns `NULL`. The returned value should be freed when no longer needed.

`str` : | the string to duplicate part of.
`n` : | the maximum number of characters to copy from `str`.
Returns : | a newly-allocated buffer containing the first `n` characters of `str`, nul-terminated.

### g_strdupv ()

    gchar**     g_strdupv                       (gchar **str_array);

Copies `NULL`-terminated array of strings. The copy is a deep copy; the new array should be freed by first freeing each string, then the array itself. `g_strfreev()` does this for you. If called on a `NULL` value, `g_strdupv()` simply returns `NULL`.

`str_array` : | `NULL`-terminated array of strings.
Returns : | a new `NULL`-terminated array of strings.

### g_strnfill ()

    gchar*      g_strnfill                      (gsize length,
                                                 gchar fill_char);

Creates a new string `length` characters long filled with `fill_char`. The returned string should be freed when no longer needed.

`length` : | the length of the new string.
`fill_char` : | the character to fill the string with.
Returns : | a newly-allocated string filled the `fill_char`.

### g_stpcpy ()

    gchar*      g_stpcpy                        (gchar *dest,
                                                 const char *src);

Copies a nul-terminated string into the dest buffer, include the trailing nul, and return a pointer to the trailing nul byte. This is useful for concatenating multiple strings together without having to repeatedly scan for the end.

`dest` : | destination buffer.
`src` : | source string.
Returns : | a pointer to trailing nul byte.

### g_strstr_len ()

    gchar*      g_strstr_len                    (const gchar *haystack,
                                                 gssize haystack_len,
                                                 const gchar *needle);

Searches the string `haystack` for the first occurrence of the string `needle`, limiting the length of the search to `haystack_len`.

`haystack` : | a string.
`haystack_len` : | the maximum length of `haystack`.
`needle` : | the string to search for.
Returns : | a pointer to the found occurrence, or `NULL` if not found.

### g_strrstr ()

    gchar*      g_strrstr                       (const gchar *haystack,
                                                 const gchar *needle);

Searches the string `haystack` for the last occurrence of the string `needle`.

`haystack` : | a nul-terminated string.
`needle` : | the nul-terminated string to search for.
Returns : | a pointer to the found occurrence, or `NULL` if not found.

### g_strrstr_len ()

    gchar*      g_strrstr_len                   (const gchar *haystack,
                                                 gssize haystack_len,
                                                 const gchar *needle);

Searches the string `haystack` for the last occurrence of the string `needle`, limiting the length of the search to `haystack_len`.

`haystack` : | a nul-terminated string.
`haystack_len` : | the maximum length of `haystack`.
`needle` : | the nul-terminated string to search for.
Returns : | a pointer to the found occurrence, or `NULL` if not found.

### g_str_has_prefix ()

    gboolean    g_str_has_prefix                (const gchar *str,
                                                 const gchar *prefix);

Looks whether the string `str` begins with `prefix`.

`str` : | a nul-terminated string.
`prefix` : | the nul-terminated prefix to look for.
Returns : | `TRUE` if `str` begins with `prefix`, `FALSE` otherwise.

Since 2.2

### g_str_has_suffix ()

    gboolean    g_str_has_suffix                (const gchar *str,
                                                 const gchar *suffix);

Looks whether the string `str` ends with `suffix`.

`str` : | a nul-terminated string.
`suffix` : | the nul-terminated suffix to look for.
Returns : | `TRUE` if `str` end with `suffix`, `FALSE` otherwise.

Since 2.2

### g_strlcpy ()

    gsize       g_strlcpy                       (gchar *dest,
                                                 const gchar *src,
                                                 gsize dest_size);

Portability wrapper that calls `strlcpy()` on systems which have it, and emulates `strlcpy()` otherwise. Copies `src` to `dest`; `dest` is guaranteed to be nul-terminated; `src` must be nul-terminated; `dest_size` is the buffer size, not the number of chars to copy. Caveat: `strlcpy()` is supposedly more secure than `strcpy()` or `strncpy()`, but if you really want to avoid screwups, `g_strdup()` is an even better idea.

`dest` : | destination buffer
`src` : | source buffer
`dest_size` : | length of `dest` in bytes
Returns : | length of `src`

### g_strlcat ()

    gsize       g_strlcat                       (gchar *dest,
                                                 const gchar *src,
                                                 gsize dest_size);

Portability wrapper that calls `strlcat()` on systems which have it, and emulates it otherwise. Appends nul-terminated `src` string to `dest`, guaranteeing nul-termination for `dest`. The total size of `dest` won't exceed `dest_size`. Caveat: this is supposedly a more secure alternative to `strcat()` or `strncat()`, but for real security `g_strconcat()` is harder to mess up.

`dest` : | destination buffer, already containing one nul-terminated string
`src` : | source buffer
`dest_size` : | length of `dest` buffer in bytes (not length of existing string inside `dest`)
Returns : | length of `src` plus initial length of string in `dest`

### g_strdup_printf ()

    gchar*      g_strdup_printf                 (const gchar *format,
                                                 ...);

Similar to the standard C `sprintf()` function but safer, since it calculates the maximum space required and allocates memory to hold the result. The returned string should be freed when no longer needed.

`format` : | a standard `printf()` format string, but notice string precision pitfalls.
`...` : | the parameters to insert into the format string.
Returns : | a newly-allocated string holding the result.

### g_strdup_vprintf ()

    gchar*      g_strdup_vprintf                (const gchar *format,
                                                 va_list args);

Similar to the standard C `vsprintf()` function but safer, since it calculates the maximum space required and allocates memory to hold the result. The returned string should be freed when no longer needed.

See also `g_vasprintf()`, which offers the same functionality, but additionally returns the length of the allocated string.

`format` : | a standard `printf()` format string, but notice string precision pitfalls.
`args` : | the list of parameters to insert into the format string.
Returns : | a newly-allocated string holding the result.

### g_printf ()

    gint        g_printf                        (gchar const *format,
                                                 ...);

An implementation of the standard `printf()` function which supports positional parameters, as specified in the Single Unix Specification.

`format` : | a standard `printf()` format string, but notice string precision pitfalls.
`...` : | the arguments to insert in the output.
Returns : | the number of characters printed.

Since 2.2

### g_vprintf ()

    gint        g_vprintf                       (gchar const *format,
                                                 va_list args);

An implementation of the standard `vprintf()` function which supports positional parameters, as specified in the Single Unix Specification.

`format` : | a standard `printf()` format string, but notice string precision pitfalls.
`args` : | the list of arguments to insert in the output.
Returns : | the number of characters printed.

Since 2.2

### g_fprintf ()

    gint        g_fprintf                       (FILE *file,
                                                 gchar const *format,
                                                 ...);

An implementation of the standard `fprintf()` function which supports positional parameters, as specified in the Single Unix Specification.

`file` : | the stream to write to.
`format` : | a standard `printf()` format string, but notice string precision pitfalls.
`...` : | the arguments to insert in the output.
Returns : | the number of characters printed.

Since 2.2

### g_vfprintf ()

    gint        g_vfprintf                      (FILE *file,
                                                 gchar const *format,
                                                 va_list args);

An implementation of the standard `fprintf()` function which supports positional parameters, as specified in the Single Unix Specification.

`file` : | the stream to write to.
`format` : | a standard `printf()` format string, but notice string precision pitfalls.
`args` : | the list of arguments to insert in the output.
Returns : | the number of characters printed.

Since 2.2

### g_sprintf ()

    gint        g_sprintf                       (gchar *string,
                                                 gchar const *format,
                                                 ...);

An implementation of the standard `sprintf()` function which supports positional parameters, as specified in the Single Unix Specification.

`string` : | the buffer to hold the output.
`format` : | a standard `printf()` format string, but notice string precision pitfalls.
`...` : | the arguments to insert in the output.
Returns : | the number of characters printed.

Since 2.2

### g_vsprintf ()

    gint        g_vsprintf                      (gchar *string,
                                                 gchar const *format,
                                                 va_list args);

An implementation of the standard `vsprintf()` function which supports positional parameters, as specified in the Single Unix Specification.

`string` : | the buffer to hold the output.
`format` : | a standard `printf()` format string, but notice string precision pitfalls.
`args` : | the list of arguments to insert in the output.
Returns : | the number of characters printed.

Since 2.2

### g_snprintf ()

    gint        g_snprintf                      (gchar *string,
                                                 gulong n,
                                                 gchar const *format,
                                                 ...);

A safer form of the standard `sprintf()` function. The output is guaranteed to not exceed `n` characters (including the terminating nul character), so it is easy to ensure that a buffer overflow cannot occur.

See also `g_strdup_printf()`.

In versions of GLib prior to 1.2.3, this function may return -1 if the output was truncated, and the truncated string may not be nul-terminated. In versions prior to 1.3.12, this function returns the length of the output string.

The return value of `g_snprintf()` conforms to the `snprintf()` function as standardized in ISO C99. Note that this is different from traditional `snprintf()`, which returns the length of the output string.

The format string may contain positional parameters, as specified in the Single Unix Specification.

`string` : | the buffer to hold the output.
`n` : | the maximum number of characters to produce (including the terminating nul character).
`format` : | a standard `printf()` format string, but notice string precision pitfalls.
`...` : | the arguments to insert in the output.
Returns : | the number of characters which would be produced if the buffer was large enough.

### g_vsnprintf ()

    gint        g_vsnprintf                     (gchar *string,
                                                 gulong n,
                                                 gchar const *format,
                                                 va_list args);

A safer form of the standard `vsprintf()` function. The output is guaranteed to not exceed `n` characters (including the terminating nul character), so it is easy to ensure that a buffer overflow cannot occur.

See also `g_strdup_vprintf()`.

In versions of GLib prior to 1.2.3, this function may return -1 if the output was truncated, and the truncated string may not be nul-terminated. In versions prior to 1.3.12, this function returns the length of the output string.

The return value of `g_vsnprintf()` conforms to the `vsnprintf()` function as standardized in ISO C99. Note that this is different from traditional `vsnprintf()`, which returns the length of the output string.

The format string may contain positional parameters, as specified in the Single Unix Specification.

`string` : | the buffer to hold the output.
`n` : | the maximum number of characters to produce (including the terminating nul character).
`format` : | a standard `printf()` format string, but notice string precision pitfalls.
`args` : | the list of arguments to insert in the output.
Returns : | the number of characters which would be produced if the buffer was large enough.

### g_vasprintf ()

    gint        g_vasprintf                     (gchar **string,
                                                 gchar const *format,
                                                 va_list args);

An implementation of the GNU `vasprintf()` function which supports positional parameters, as specified in the Single Unix Specification. This function is similar to `g_vsprintf()`, except that it allocates a string to hold the output, instead of putting the output in a buffer you allocate in advance.

`string` : | the return location for the newly-allocated string.
`format` : | a standard `printf()` format string, but notice string precision pitfalls.
`args` : | the list of arguments to insert in the output.
Returns : | the number of characters printed.

Since 2.4

### g_printf_string_upper_bound ()

    gsize       g_printf_string_upper_bound     (const gchar *format,
                                                 va_list args);

Calculates the maximum space needed to store the output of the `sprintf()` function.

`format` : | the format string. See the `printf()` documentation.
`args` : | the parameters to be inserted into the format string.
Returns : | the maximum space needed to store the formatted string.

### g_ascii_isalnum ()

    gboolean    g_ascii_isalnum                 (gchar c);

Determines whether a character is alphanumeric.

Unlike the standard C library `isalnum()` function, this only recognizes standard ASCII letters and ignores the locale, returning `FALSE` for all non-ASCII characters. Also unlike the standard library function, this takes a char, not an int, so don't call it on `EOF` but no need to cast to guchar before passing a possibly non-ASCII character in.

`c` : | any character
Returns : | `TRUE` if `c` is an ASCII alphanumeric character

### g_ascii_isalpha ()

    gboolean    g_ascii_isalpha                 (gchar c);

Determines whether a character is alphabetic (i.e. a letter).

Unlike the standard C library `isalpha()` function, this only recognizes standard ASCII letters and ignores the locale, returning `FALSE` for all non-ASCII characters. Also unlike the standard library function, this takes a char, not an int, so don't call it on `EOF` but no need to cast to guchar before passing a possibly non-ASCII character in.

`c` : | any character
Returns : | `TRUE` if `c` is an ASCII alphabetic character

### g_ascii_iscntrl ()

    gboolean    g_ascii_iscntrl                 (gchar c);

Determines whether a character is a control character.

Unlike the standard C library `iscntrl()` function, this only recognizes standard ASCII control characters and ignores the locale, returning `FALSE` for all non-ASCII characters. Also unlike the standard library function, this takes a char, not an int, so don't call it on `EOF` but no need to cast to guchar before passing a possibly non-ASCII character in.

`c` : | any character
Returns : | `TRUE` if `c` is an ASCII control character.

### g_ascii_isdigit ()

    gboolean    g_ascii_isdigit                 (gchar c);

Determines whether a character is digit (0-9).

Unlike the standard C library `isdigit()` function, this takes a char, not an int, so don't call it on `EOF` but no need to cast to guchar before passing a possibly non-ASCII character in.

`c` : | any character
Returns : | `TRUE` if `c` is an ASCII digit.

### g_ascii_isgraph ()

    gboolean    g_ascii_isgraph                 (gchar c);

Determines whether a character is a printing character and not a space.

Unlike the standard C library `isgraph()` function, this only recognizes standard ASCII characters and ignores the locale, returning `FALSE` for all non-ASCII characters. Also unlike the standard library function, this takes a char, not an int, so don't call it on `EOF` but no need to cast to guchar before passing a possibly non-ASCII character in.

`c` : | any character
Returns : | `TRUE` if `c` is an ASCII printing character other than space.

### g_ascii_islower ()

    gboolean    g_ascii_islower                 (gchar c);

Determines whether a character is an ASCII lower case letter.

Unlike the standard C library `islower()` function, this only recognizes standard ASCII letters and ignores the locale, returning `FALSE` for all non-ASCII characters. Also unlike the standard library function, this takes a char, not an int, so don't call it on `EOF` but no need to worry about casting to guchar before passing a possibly non-ASCII character in.

`c` : | any character
Returns : | `TRUE` if `c` is an ASCII lower case letter

### g_ascii_isprint ()

    gboolean    g_ascii_isprint                 (gchar c);

Determines whether a character is a printing character.

Unlike the standard C library `isprint()` function, this only recognizes standard ASCII characters and ignores the locale, returning `FALSE` for all non-ASCII characters. Also unlike the standard library function, this takes a char, not an int, so don't call it on `EOF` but no need to cast to guchar before passing a possibly non-ASCII character in.

`c` : | any character
Returns : | `TRUE` if `c` is an ASCII printing character.

### g_ascii_ispunct ()

    gboolean    g_ascii_ispunct                 (gchar c);

Determines whether a character is a punctuation character.

Unlike the standard C library `ispunct()` function, this only recognizes standard ASCII letters and ignores the locale, returning `FALSE` for all non-ASCII characters. Also unlike the standard library function, this takes a char, not an int, so don't call it on `EOF` but no need to cast to guchar before passing a possibly non-ASCII character in.

`c` : | any character
Returns : | `TRUE` if `c` is an ASCII punctuation character.

### g_ascii_isspace ()

    gboolean    g_ascii_isspace                 (gchar c);

Determines whether a character is a white-space character.

Unlike the standard C library `isspace()` function, this only recognizes standard ASCII white-space and ignores the locale, returning `FALSE` for all non-ASCII characters. Also unlike the standard library function, this takes a char, not an int, so don't call it on `EOF` but no need to cast to guchar before passing a possibly non-ASCII character in.

`c` : | any character
Returns : | `TRUE` if `c` is an ASCII white-space character

### g_ascii_isupper ()

    gboolean    g_ascii_isupper                 (gchar c);

Determines whether a character is an ASCII upper case letter.

Unlike the standard C library `isupper()` function, this only recognizes standard ASCII letters and ignores the locale, returning `FALSE` for all non-ASCII characters. Also unlike the standard library function, this takes a char, not an int, so don't call it on `EOF` but no need to worry about casting to guchar before passing a possibly non-ASCII character in.

`c` : | any character
Returns : | `TRUE` if `c` is an ASCII upper case letter

### g_ascii_isxdigit ()

    gboolean    g_ascii_isxdigit                (gchar c);

Determines whether a character is a hexadecimal-digit character.

Unlike the standard C library `isxdigit()` function, this takes a char, not an int, so don't call it on `EOF` but no need to cast to guchar before passing a possibly non-ASCII character in.

`c` : | any character
Returns : | `TRUE` if `c` is an ASCII hexadecimal-digit character.

### g_ascii_digit_value ()

    gint        g_ascii_digit_value             (gchar c);

Determines the numeric value of a character as a decimal digit. Differs from `g_unichar_digit_value()` because it takes a char, so there's no worry about sign extension if characters are signed.

`c` : | an ASCII character.
Returns : | If `c` is a decimal digit (according to `g_ascii_isdigit()`), its numeric value. Otherwise, -1.

### g_ascii_xdigit_value ()

    gint        g_ascii_xdigit_value            (gchar c);

Determines the numeric value of a character as a hexidecimal digit. Differs from `g_unichar_xdigit_value()` because it takes a char, so there's no worry about sign extension if characters are signed.

`c` : | an ASCII character.
Returns : | If `c` is a hex digit (according to `g_ascii_isxdigit()`), its numeric value. Otherwise, -1.

### g_ascii_strcasecmp ()

    gint        g_ascii_strcasecmp              (const gchar *s1,
                                                 const gchar *s2);

Compare two strings, ignoring the case of ASCII characters.

Unlike the BSD `strcasecmp()` function, this only recognizes standard ASCII letters and ignores the locale, treating all non-ASCII characters as if they are not letters.

`s1` : | string to compare with `s2`.
`s2` : | string to compare with `s1`.
Returns : | an integer less than, equal to, or greater than zero if `s1` is found, respectively, to be less than, to match, or to be greater than `s2`.

### g_ascii_strncasecmp ()

    gint        g_ascii_strncasecmp             (const gchar *s1,
                                                 const gchar *s2,
                                                 gsize n);

Compare `s1` and `s2`, ignoring the case of ASCII characters and any characters after the first `n` in each string.

Unlike the BSD `strcasecmp()` function, this only recognizes standard ASCII letters and ignores the locale, treating all non-ASCII characters as if they are not letters.

`s1` : | string to compare with `s2`.
`s2` : | string to compare with `s1`.
`n` : | number of characters to compare.
Returns : | an integer less than, equal to, or greater than zero if the first `n` bytes of `s1` is found, respectively, to be less than, to match, or to be greater than the first `n` bytes of `s2`.

### g_ascii_strup ()

    gchar*      g_ascii_strup                   (const gchar *str,
                                                 gssize len);

Converts all lower case ASCII letters to upper case ASCII letters.

`str` : | a string.
`len` : | length of `str` in bytes, or -1 if `str` is nul-terminated.
Returns : | a newly allocated string, with all the lower case characters in `str` converted to upper case, with semantics that exactly match `g_ascii_toupper()`. (Note that this is unlike the old `g_strup()`, which modified the string in place.)

### g_ascii_strdown ()

    gchar*      g_ascii_strdown                 (const gchar *str,
                                                 gssize len);

Converts all upper case ASCII letters to lower case ASCII letters.

`str` : | a string.
`len` : | length of `str` in bytes, or -1 if `str` is nul-terminated.
Returns : | a newly-allocated string, with all the upper case characters in `str` converted to lower case, with semantics that exactly match `g_ascii_tolower()`. (Note that this is unlike the old `g_strdown()`, which modified the string in place.)

### g_ascii_tolower ()

    gchar       g_ascii_tolower                 (gchar c);

Convert a character to ASCII lower case.

Unlike the standard C library `tolower()` function, this only recognizes standard ASCII letters and ignores the locale, returning all non-ASCII characters unchanged, even if they are lower case letters in a particular character set. Also unlike the standard library function, this takes and returns a char, not an int, so don't call it on `EOF` but no need to worry about casting to guchar before passing a possibly non-ASCII character in.

`c` : | any character.
Returns : | the result of converting `c` to lower case. If `c` is not an ASCII upper case letter, `c` is returned unchanged.

### g_ascii_toupper ()

    gchar       g_ascii_toupper                 (gchar c);

Convert a character to ASCII upper case.

Unlike the standard C library `toupper()` function, this only recognizes standard ASCII letters and ignores the locale, returning all non-ASCII characters unchanged, even if they are upper case letters in a particular character set. Also unlike the standard library function, this takes and returns a char, not an int, so don't call it on `EOF` but no need to worry about casting to guchar before passing a possibly non-ASCII character in.

`c` : | any character.
Returns : | the result of converting `c` to upper case. If `c` is not an ASCII lower case letter, `c` is returned unchanged.

### g_string_ascii_up ()

    GString*    g_string_ascii_up               (GString *string);

Converts all lower case ASCII letters to upper case ASCII letters.

`string` : | a GString
Returns : | passed-in `string` pointer, with all the lower case characters converted to upper case in place, with semantics that exactly match g_ascii_toupper.

### g_string_ascii_down ()

    GString*    g_string_ascii_down             (GString *string);

Converts all upper case ASCII letters to lower case ASCII letters.

`string` : | a GString
Returns : | passed-in `string` pointer, with all the upper case characters converted to lower case in place, with semantics that exactly match g_ascii_tolower.

### g_strup ()

    gchar*      g_strup                         (gchar *string);

### Warning

`g_strup` is deprecated and should not be used in newly-written code. This function is totally broken for the reasons discussed in the `g_strncasecmp()` docs - use `g_ascii_strup()` or `g_utf8_strup()` instead.

Converts a string to upper case.

`string` : | the string to convert.
Returns : | the string

### g_strdown ()

    gchar*      g_strdown                       (gchar *string);

### Warning

`g_strdown` is deprecated and should not be used in newly-written code. This function is totally broken for the reasons discussed in the `g_strncasecmp()` docs - use `g_ascii_strdown()` or `g_utf8_strdown()` instead.

Converts a string to lower case.

`string` : | the string to convert.
Returns : | the string

### g_strcasecmp ()

    gint        g_strcasecmp                    (const gchar *s1,
                                                 const gchar *s2);

### Warning

`g_strcasecmp` is deprecated and should not be used in newly-written code. See `g_strncasecmp()` for a discussion of why this function is deprecated and how to replace it.

A case-insensitive string comparison, corresponding to the standard `strcasecmp()` function on platforms which support it.

`s1` : | a string.
`s2` : | a string to compare with `s1`.
Returns : | 0 if the strings match, a negative value if `s1` < `s2`, or a positive value if `s1` > `s2`.

### g_strncasecmp ()

    gint        g_strncasecmp                   (const gchar *s1,
                                                 const gchar *s2,
                                                 guint n);

### Warning

`g_strncasecmp` is deprecated and should not be used in newly-written code. The problem with `g_strncasecmp()` is that it does the comparison by calling `toupper()`/`tolower()`. These functions are locale-specific and operate on single bytes. However, it is impossible to handle things correctly from an I18N standpoint by operating on bytes, since characters may be multibyte. Thus `g_strncasecmp()` is broken if your string is guaranteed to be ASCII, since it's locale-sensitive, and it's broken if your string is localized, since it doesn't work on many encodings at all, including UTF-8, EUC-JP, etc.

There are therefore two replacement functions: `g_ascii_strncasecmp()`, which only works on ASCII and is not locale-sensitive, and `g_utf8_casefold()`, which is good for case-insensitive sorting of UTF-8.

A case-insensitive string comparison, corresponding to the standard `strncasecmp()` function on platforms which support it. It is similar to `g_strcasecmp()` except it only compares the first `n` characters of the strings.

`s1` : | a string.
`s2` : | a string to compare with `s1`.
`n` : | the maximum number of characters to compare.
Returns : | 0 if the strings match, a negative value if `s1` < `s2`, or a positive value if `s1` > `s2`.

### g_strreverse ()

    gchar*      g_strreverse                    (gchar *string);

Reverses all of the bytes in a string. For example, `g_strreverse ("abcdef")` will result in "fedcba".

Note that `g_strreverse()` doesn't work on UTF-8 strings containing multibyte characters. For that purpose, use `g_utf8_strreverse()`.

`string` : | the string to reverse.
Returns : | the same pointer passed in as `string`.

### g_ascii_strtoull ()

    guint64     g_ascii_strtoull                (const gchar *nptr,
                                                 gchar **endptr,
                                                 guint base);

Converts a string to a guint64 value. This function behaves like the standard `strtoull()` function does in the C locale. It does this without actually changing the current locale, since that would not be thread-safe.

This function is typically used when reading configuration files or other non-user input that should be locale independent. To handle input from the user you should normally use the locale-sensitive system `strtoull()` function.

If the correct value would cause overflow, `G_MAXUINT64` is returned, and `ERANGE` is stored in `errno`.

`nptr` : | the string to convert to a numeric value.
`endptr` : | if non-`NULL`, it returns the character after the last character used in the conversion.
`base` : | to be used for the conversion, 2..36 or 0
Returns : | the guint64 value.

Since 2.2

### G_ASCII_DTOSTR_BUF_SIZE

    #define G_ASCII_DTOSTR_BUF_SIZE (29 + 10)

A good size for a buffer to be passed into `g_ascii_dtostr()`. It is guaranteed to be enough for all output of that function on systems with 64bit IEEE-compatible doubles.

The typical usage would be something like:

      char buf[G_ASCII_DTOSTR_BUF_SIZE];

      fprintf (out, "value=%s\n", g_ascii_dtostr (buf, sizeof (buf), value));

### g_ascii_strtod ()

    gdouble     g_ascii_strtod                  (const gchar *nptr,
                                                 gchar **endptr);

Converts a string to a gdouble value. This function behaves like the standard `strtod()` function does in the C locale. It does this without actually changing the current locale, since that would not be thread-safe.

This function is typically used when reading configuration files or other non-user input that should be locale independent. To handle input from the user you should normally use the locale-sensitive system `strtod()` function.

To convert from a gdouble to a string in a locale-insensitive way, use `g_ascii_dtostr()`.

If the correct value would cause overflow, plus or minus `HUGE_VAL` is returned (according to the sign of the value), and `ERANGE` is stored in `errno`. If the correct value would cause underflow, zero is returned and `ERANGE` is stored in `errno`.

This function resets `errno` before calling `strtod()` so that you can reliably detect overflow and underflow.

`nptr` : | the string to convert to a numeric value.
`endptr` : | if non-`NULL`, it returns the character after the last character used in the conversion.
Returns : | the gdouble value.

### g_ascii_dtostr ()

    gchar*      g_ascii_dtostr                  (gchar *buffer,
                                                 gint buf_len,
                                                 gdouble d);

Converts a gdouble to a string, using the '.' as decimal point.

This functions generates enough precision that converting the string back using `g_ascii_strtod()` gives the same machine-number (on machines with IEEE compatible 64bit doubles). It is guaranteed that the size of the resulting string will never be larger than `G_ASCII_DTOSTR_BUF_SIZE` bytes.

`buffer` : | A buffer to place the resulting string in
`buf_len` : | The length of the buffer.
`d` : | The gdouble to convert
Returns : | The pointer to the buffer with the converted string.

### g_ascii_formatd ()

    gchar*      g_ascii_formatd                 (gchar *buffer,
                                                 gint buf_len,
                                                 const gchar *format,
                                                 gdouble d);

Converts a gdouble to a string, using the '.' as decimal point. To format the number you pass in a `printf()`-style format string. Allowed conversion specifiers are 'e', 'E', 'f', 'F', 'g' and 'G'.

If you just want to want to serialize the value into a string, use `g_ascii_dtostr()`.

`buffer` : | A buffer to place the resulting string in
`buf_len` : | The length of the buffer.
`format` : | The `printf()`-style format to use for the code to use for converting.
`d` : | The gdouble to convert
Returns : | The pointer to the buffer with the converted string.

### g_strtod ()

    gdouble     g_strtod                        (const gchar *nptr,
                                                 gchar **endptr);

Converts a string to a gdouble value. It calls the standard `strtod()` function to handle the conversion, but if the string is not completely converted it attempts the conversion again with `g_ascii_strtod()`, and returns the best match.

This function should seldomly be used. The normal situation when reading numbers not for human consumption is to use `g_ascii_strtod()`. Only when you know that you must expect both locale formatted and C formatted numbers should you use this. Make sure that you don't pass strings such as comma separated lists of values, since the commas may be interpreted as a decimal point in some locales, causing unexpected results.

`nptr` : | the string to convert to a numeric value.
`endptr` : | if non-`NULL`, it returns the character after the last character used in the conversion.
Returns : | the gdouble value.

### g_strchug ()

    gchar*      g_strchug                       (gchar *string);

Removes leading whitespace from a string, by moving the rest of the characters forward.

`string` : | a string to remove the leading whitespace from.
Returns : | `string`.

### g_strchomp ()

    gchar*      g_strchomp                      (gchar *string);

Removes trailing whitespace from a string.

`string` : | a string to remove the trailing whitespace from.
Returns : | `string`.

### g_strstrip()

    #define     g_strstrip( string )

Removes leading and trailing whitespace from a string.

`string` : | a string to remove the leading and trailing whitespace from.

### g_strdelimit ()

    gchar*      g_strdelimit                    (gchar *string,
                                                 const gchar *delimiters,
                                                 gchar new_delimiter);

Converts any delimiter characters in `string` to `new_delimiter`. Any characters in `string` which are found in `delimiters` are changed to the `new_delimiter` character. Modifies `string` in place, and returns `string` itself, not a copy. The return value is to allow nesting such as `g_ascii_strup (g_strdelimit (str, "abc", '?'))`.

`string` : | the string to convert.
`delimiters` : | a string containing the current delimiters, or `NULL` to use the standard delimiters defined in G_STR_DELIMITERS.
`new_delimiter` : | the new delimiter character.
Returns : | `string`.

### G_STR_DELIMITERS

    #define	 G_STR_DELIMITERS	"_-|> <."

The standard delimiters, used in `g_strdelimit()`.

### g_strescape ()

    gchar*      g_strescape                     (const gchar *source,
                                                 const gchar *exceptions);

Escapes the special characters '\b', '\f', '\n', '\r', '\t', '\' and '"' in the string `source` by inserting a '\' before them. Additionally all characters in the range 0x01-0x1F (everything below SPACE) and in the range 0x7F-0xFF (all non-ASCII chars) are replaced with a '\' followed by their octal representation. Characters supplied in `exceptions` are not escaped.

`g_strcompress()` does the reverse conversion.

`source` : | a string to escape.
`exceptions` : | a string of characters not to escape in `source`.
Returns : | a newly-allocated copy of `source` with certain characters escaped. See above.

### g_strcompress ()

    gchar*      g_strcompress                   (const gchar *source);

Replaces all escaped characters with their one byte equivalent. It does the reverse conversion of `g_strescape()`.

`source` : | a string to compress.
Returns : | a newly-allocated copy of `source` with all escaped character compressed.

### g_strcanon ()

    gchar*      g_strcanon                      (gchar *string,
                                                 const gchar *valid_chars,
                                                 gchar substitutor);

For each character in `string`, if the character is not in `valid_chars`, replaces the character with `substitutor`. Modifies `string` in place, and return `string` itself, not a copy. The return value is to allow nesting such as `g_ascii_strup (g_strcanon (str, "abc", '?'))`.

`string` : | a nul-terminated array of bytes.
`valid_chars` : | bytes permitted in `string`.
`substitutor` : | replacement character for disallowed bytes.
Returns : | `string`.

### g_strsplit ()

    gchar**     g_strsplit                      (const gchar *string,
                                                 const gchar *delimiter,
                                                 gint max_tokens);

Splits a string into a maximum of `max_tokens` pieces, using the given `delimiter`. If `max_tokens` is reached, the remainder of `string` is appended to the last token.

As a special case, the result of splitting the empty string "" is an empty vector, not a vector containing a single string. The reason for this special case is that being able to represent a empty vector is typically more useful than consistent handling of empty elements. If you do need to represent empty elements, you'll need to check for the empty string before calling `g_strsplit()`.

`string` : | a string to split.
`delimiter` : | a string which specifies the places at which to split the string. The delimiter is not included in any of the resulting strings, unless `max_tokens` is reached.
`max_tokens` : | the maximum number of pieces to split `string` into. If this is less than 1, the string is split completely.
Returns : | a newly-allocated `NULL`-terminated array of strings. Use `g_strfreev()` to free it.

### g_strsplit_set ()

    gchar**     g_strsplit_set                  (const gchar *string,
                                                 const gchar *delimiters,
                                                 gint max_tokens);

Splits `string` into a number of tokens not containing any of the characters in `delimiter`. A token is the (possibly empty) longest string that does not contain any of the characters in `delimiters`. If `max_tokens` is reached, the remainder is appended to the last token.

For example the result of g_strsplit_set ("abc:def/ghi", ":/", -1) is a `NULL`-terminated vector containing the three strings "abc", "def", and "ghi".

The result if g_strsplit_set (":def/ghi:", ":/", -1) is a `NULL`-terminated vector containing the four strings "", "def", "ghi", and "".

As a special case, the result of splitting the empty string "" is an empty vector, not a vector containing a single string. The reason for this special case is that being able to represent a empty vector is typically more useful than consistent handling of empty elements. If you do need to represent empty elements, you'll need to check for the empty string before calling `g_strsplit_set()`.

Note that this function works on bytes not characters, so it can't be used to delimit UTF-8 strings for anything but ASCII characters.

`string` : | The string to be tokenized
`delimiters` : | A nul-terminated string containing bytes that are used to split the string.
`max_tokens` : | The maximum number of tokens to split `string` into. If this is less than 1, the string is split completely
Returns : | a newly-allocated `NULL`-terminated array of strings. Use `g_strfreev()` to free it.

Since 2.4

### g_strfreev ()

    void        g_strfreev                      (gchar **str_array);

Frees a `NULL`-terminated array of strings, and the array itself. If called on a `NULL` value, `g_strfreev()` simply returns.

`str_array` : | a `NULL`-terminated array of strings to free.

### g_strconcat ()

    gchar*      g_strconcat                     (const gchar *string1,
                                                 ...);

Concatenates all of the given strings into one long string. The returned string should be freed when no longer needed.

### Warning

The variable argument list must end with `NULL`. If you forget the `NULL`, `g_strconcat()` will start appending random memory junk to your string.

`string1` : | The first string to add, which must not be `NULL`.
`...` : | a `NULL`-terminated list of strings to append to the string.
Returns : | a newly-allocated string containing all the string arguments.

### g_strjoin ()

    gchar*      g_strjoin                       (const gchar *separator,
                                                 ...);

Joins a number of strings together to form one long string, with the optional `separator` inserted between each of them.

`separator` : | a string to insert between each of the strings, or `NULL`.
`...` : | a `NULL`-terminated list of strings to join.
Returns : | a newly-allocated string containing all of the strings joined together, with `separator` between them.

### g_strjoinv ()

    gchar*      g_strjoinv                      (const gchar *separator,
                                                 gchar **str_array);

Joins a number of strings together to form one long string, with the optional `separator` inserted between each of them.

`separator` : | a string to insert between each of the strings, or `NULL`.
`str_array` : | a `NULL`-terminated array of strings to join.
Returns : | a newly-allocated string containing all of the strings joined together, with `separator` between them.

### g_strv_length ()

    guint       g_strv_length                   (gchar **str_array);

Returns the length of the given `NULL`-terminated string array `str_array`.

`str_array` : | a `NULL`-terminated array of strings.
Returns : | length of `str_array`.

Since 2.6

### g_strerror ()

    const gchar* g_strerror                     (gint errnum);

Returns a string corresponding to the given error code, e.g. "no such process". This function is included since not all platforms support the `strerror()` function.

`errnum` : | the system error number. See the standard C `errno` documentation.
Returns : | a string describing the error code. If the error code is unknown, it returns "unknown error (<code>)". The string can only be used until the next call to `g_strerror()`.

### g_strsignal ()

    const gchar* g_strsignal                    (gint signum);

Returns a string describing the given signal, e.g. "Segmentation fault". This function is included since not all platforms support the `strsignal()` function.

`signum` : | the signal number. See the `signal` documentation.
Returns : | a string describing the signal. If the signal is unknown, it returns "unknown signal (<signum>)". The string can only be used until the next call to `g_strsignal()`.