## Unicode Manipulation Unicode Manipulation — functions operating on Unicode characters and UTF-8 strings. |

## Synopsis

    #include <glib.h>

    typedef     gunichar;
    typedef     gunichar2;

    gboolean    g_unichar_validate              (gunichar ch);
    gboolean    g_unichar_isalnum               (gunichar c);
    gboolean    g_unichar_isalpha               (gunichar c);
    gboolean    g_unichar_iscntrl               (gunichar c);
    gboolean    g_unichar_isdigit               (gunichar c);
    gboolean    g_unichar_isgraph               (gunichar c);
    gboolean    g_unichar_islower               (gunichar c);
    gboolean    g_unichar_isprint               (gunichar c);
    gboolean    g_unichar_ispunct               (gunichar c);
    gboolean    g_unichar_isspace               (gunichar c);
    gboolean    g_unichar_isupper               (gunichar c);
    gboolean    g_unichar_isxdigit              (gunichar c);
    gboolean    g_unichar_istitle               (gunichar c);
    gboolean    g_unichar_isdefined             (gunichar c);
    gboolean    g_unichar_iswide                (gunichar c);
    gunichar    g_unichar_toupper               (gunichar c);
    gunichar    g_unichar_tolower               (gunichar c);
    gunichar    g_unichar_totitle               (gunichar c);
    gint        g_unichar_digit_value           (gunichar c);
    gint        g_unichar_xdigit_value          (gunichar c);
    enum        GUnicodeType;
    GUnicodeType g_unichar_type                 (gunichar c);
    enum        GUnicodeBreakType;
    GUnicodeBreakType g_unichar_break_type      (gunichar c);
    void        g_unicode_canonical_ordering    (gunichar *string,
                                                 gsize len);
    gunichar*   g_unicode_canonical_decomposition
                                                (gunichar ch,
                                                 gsize *result_len);
    gboolean    g_unichar_get_mirror_char       (gunichar ch,
                                                 gunichar *mirrored_ch);

    #define     g_utf8_next_char                (p)
    gunichar    g_utf8_get_char                 (const gchar *p);
    gunichar    g_utf8_get_char_validated       (const  gchar *p,
                                                 gssize max_len);
    gchar*      g_utf8_offset_to_pointer        (const gchar *str,
                                                 glong offset);
    glong       g_utf8_pointer_to_offset        (const gchar *str,
                                                 const gchar *pos);
    gchar*      g_utf8_prev_char                (const gchar *p);
    gchar*      g_utf8_find_next_char           (const gchar *p,
                                                 const gchar *end);
    gchar*      g_utf8_find_prev_char           (const gchar *str,
                                                 const gchar *p);
    glong       g_utf8_strlen                   (const gchar *p,
                                                 gssize max);
    gchar*      g_utf8_strncpy                  (gchar *dest,
                                                 const gchar *src,
                                                 gsize n);
    gchar*      g_utf8_strchr                   (const gchar *p,
                                                 gssize len,
                                                 gunichar c);
    gchar*      g_utf8_strrchr                  (const gchar *p,
                                                 gssize len,
                                                 gunichar c);
    gchar*      g_utf8_strreverse               (const gchar *str,
                                                 gssize len);
    gboolean    g_utf8_validate                 (const gchar *str,
                                                 gssize max_len,
                                                 const gchar **end);

    gchar*      g_utf8_strup                    (const gchar *str,
                                                 gssize len);
    gchar*      g_utf8_strdown                  (const gchar *str,
                                                 gssize len);
    gchar*      g_utf8_casefold                 (const gchar *str,
                                                 gssize len);
    gchar*      g_utf8_normalize                (const gchar *str,
                                                 gssize len,
                                                 GNormalizeMode mode);
    enum        GNormalizeMode;
    gint        g_utf8_collate                  (const gchar *str1,
                                                 const gchar *str2);
    gchar*      g_utf8_collate_key              (const gchar *str,
                                                 gssize len);
    gchar*      g_utf8_collate_key_for_filename (const gchar *str,
                                                 gssize len);

    gunichar2*  g_utf8_to_utf16                 (const gchar *str,
                                                 glong len,
                                                 glong *items_read,
                                                 glong *items_written,
                                                 GError **error);
    gunichar*   g_utf8_to_ucs4                  (const gchar *str,
                                                 glong len,
                                                 glong *items_read,
                                                 glong *items_written,
                                                 GError **error);
    gunichar*   g_utf8_to_ucs4_fast             (const gchar *str,
                                                 glong len,
                                                 glong *items_written);
    gunichar*   g_utf16_to_ucs4                 (const gunichar2 *str,
                                                 glong len,
                                                 glong *items_read,
                                                 glong *items_written,
                                                 GError **error);
    gchar*      g_utf16_to_utf8                 (const gunichar2 *str,
                                                 glong len,
                                                 glong *items_read,
                                                 glong *items_written,
                                                 GError **error);
    gunichar2*  g_ucs4_to_utf16                 (const gunichar *str,
                                                 glong len,
                                                 glong *items_read,
                                                 glong *items_written,
                                                 GError **error);
    gchar*      g_ucs4_to_utf8                  (const gunichar *str,
                                                 glong len,
                                                 glong *items_read,
                                                 glong *items_written,
                                                 GError **error);
    gint        g_unichar_to_utf8               (gunichar c,
                                                 gchar *outbuf);

## Description

This section describes a number of functions for dealing with Unicode characters and strings. There are analogues of the traditional `ctype.h` character classification and case conversion functions, UTF-8 analogues of some string utility functions, functions to perform normalization, case conversion and collation on UTF-8 strings and finally functions to convert between the UTF-8, UTF-16 and UCS-4 encodings of Unicode.

## Details

### gunichar

    typedef guint32 gunichar;

A type which can hold any UCS-4 character code.

### gunichar2

    typedef guint16 gunichar2;

A type which can hold any UTF-16 code point[3].

### g_unichar_validate ()

    gboolean    g_unichar_validate              (gunichar ch);

Checks whether `ch` is a valid Unicode character. Some possible integer values of `ch` will not be valid. 0 is considered a valid character, though it's normally a string terminator.

`ch` : | a Unicode character
Returns : | `TRUE` if `ch` is a valid Unicode character

### g_unichar_isalnum ()

    gboolean    g_unichar_isalnum               (gunichar c);

Determines whether a character is alphanumeric. Given some UTF-8 text, obtain a character value with `g_utf8_get_char()`.

`c` : | a Unicode character
Returns : | `TRUE` if `c` is an alphanumeric character

### g_unichar_isalpha ()

    gboolean    g_unichar_isalpha               (gunichar c);

Determines whether a character is alphabetic (i.e. a letter). Given some UTF-8 text, obtain a character value with `g_utf8_get_char()`.

`c` : | a Unicode character
Returns : | `TRUE` if `c` is an alphabetic character

### g_unichar_iscntrl ()

    gboolean    g_unichar_iscntrl               (gunichar c);

Determines whether a character is a control character. Given some UTF-8 text, obtain a character value with `g_utf8_get_char()`.

`c` : | a Unicode character
Returns : | `TRUE` if `c` is a control character

### g_unichar_isdigit ()

    gboolean    g_unichar_isdigit               (gunichar c);

Determines whether a character is numeric (i.e. a digit). This covers ASCII 0-9 and also digits in other languages/scripts. Given some UTF-8 text, obtain a character value with `g_utf8_get_char()`.

`c` : | a Unicode character
Returns : | `TRUE` if `c` is a digit

### g_unichar_isgraph ()

    gboolean    g_unichar_isgraph               (gunichar c);

Determines whether a character is printable and not a space (returns `FALSE` for control characters, format characters, and spaces). `g_unichar_isprint()` is similar, but returns `TRUE` for spaces. Given some UTF-8 text, obtain a character value with `g_utf8_get_char()`.

`c` : | a Unicode character
Returns : | `TRUE` if `c` is printable unless it's a space

### g_unichar_islower ()

    gboolean    g_unichar_islower               (gunichar c);

Determines whether a character is a lowercase letter. Given some UTF-8 text, obtain a character value with `g_utf8_get_char()`.

`c` : | a Unicode character
Returns : | `TRUE` if `c` is a lowercase letter

### g_unichar_isprint ()

    gboolean    g_unichar_isprint               (gunichar c);

Determines whether a character is printable. Unlike `g_unichar_isgraph()`, returns `TRUE` for spaces. Given some UTF-8 text, obtain a character value with `g_utf8_get_char()`.

`c` : | a Unicode character
Returns : | `TRUE` if `c` is printable

### g_unichar_ispunct ()

    gboolean    g_unichar_ispunct               (gunichar c);

Determines whether a character is punctuation or a symbol. Given some UTF-8 text, obtain a character value with `g_utf8_get_char()`.

`c` : | a Unicode character
Returns : | `TRUE` if `c` is a punctuation or symbol character

### g_unichar_isspace ()

    gboolean    g_unichar_isspace               (gunichar c);

Determines whether a character is a space, tab, or line separator (newline, carriage return, etc.). Given some UTF-8 text, obtain a character value with `g_utf8_get_char()`.

(Note: don't use this to do word breaking; you have to use Pango or equivalent to get word breaking right, the algorithm is fairly complex.)

`c` : | a Unicode character
Returns : | `TRUE` if `c` is a space character

### g_unichar_isupper ()

    gboolean    g_unichar_isupper               (gunichar c);

Determines if a character is uppercase.

`c` : | a Unicode character
Returns : | `TRUE` if `c` is an uppercase character

### g_unichar_isxdigit ()

    gboolean    g_unichar_isxdigit              (gunichar c);

Determines if a character is a hexidecimal digit.

`c` : | a Unicode character.
Returns : | `TRUE` if the character is a hexadecimal digit

### g_unichar_istitle ()

    gboolean    g_unichar_istitle               (gunichar c);

Determines if a character is titlecase. Some characters in Unicode which are composites, such as the DZ digraph have three case variants instead of just two. The titlecase form is used at the beginning of a word where only the first letter is capitalized. The titlecase form of the DZ digraph is U+01F2 LATIN CAPITAL LETTTER D WITH SMALL LETTER Z.

`c` : | a Unicode character
Returns : | `TRUE` if the character is titlecase

### g_unichar_isdefined ()

    gboolean    g_unichar_isdefined             (gunichar c);

Determines if a given character is assigned in the Unicode standard.

`c` : | a Unicode character
Returns : | `TRUE` if the character has an assigned value

### g_unichar_iswide ()

    gboolean    g_unichar_iswide                (gunichar c);

Determines if a character is typically rendered in a double-width cell.

`c` : | a Unicode character
Returns : | `TRUE` if the character is wide

### g_unichar_toupper ()

    gunichar    g_unichar_toupper               (gunichar c);

Converts a character to uppercase.

`c` : | a Unicode character
Returns : | the result of converting `c` to uppercase. If `c` is not an lowercase or titlecase character, or has no upper case equivalent `c` is returned unchanged.

### g_unichar_tolower ()

    gunichar    g_unichar_tolower               (gunichar c);

Converts a character to lower case.

`c` : | a Unicode character.
Returns : | the result of converting `c` to lower case. If `c` is not an upperlower or titlecase character, or has no lowercase equivalent `c` is returned unchanged.

### g_unichar_totitle ()

    gunichar    g_unichar_totitle               (gunichar c);

Converts a character to the titlecase.

`c` : | a Unicode character
Returns : | the result of converting `c` to titlecase. If `c` is not an uppercase or lowercase character, `c` is returned unchanged.

### g_unichar_digit_value ()

    gint        g_unichar_digit_value           (gunichar c);

Determines the numeric value of a character as a decimal digit.

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

### g_unichar_xdigit_value ()

    gint        g_unichar_xdigit_value          (gunichar c);

Determines the numeric value of a character as a hexidecimal digit.

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

### enum GUnicodeType

    typedef enum
    {
      G_UNICODE_CONTROL,
      G_UNICODE_FORMAT,
      G_UNICODE_UNASSIGNED,
      G_UNICODE_PRIVATE_USE,
      G_UNICODE_SURROGATE,
      G_UNICODE_LOWERCASE_LETTER,
      G_UNICODE_MODIFIER_LETTER,
      G_UNICODE_OTHER_LETTER,
      G_UNICODE_TITLECASE_LETTER,
      G_UNICODE_UPPERCASE_LETTER,
      G_UNICODE_COMBINING_MARK,
      G_UNICODE_ENCLOSING_MARK,
      G_UNICODE_NON_SPACING_MARK,
      G_UNICODE_DECIMAL_NUMBER,
      G_UNICODE_LETTER_NUMBER,
      G_UNICODE_OTHER_NUMBER,
      G_UNICODE_CONNECT_PUNCTUATION,
      G_UNICODE_DASH_PUNCTUATION,
      G_UNICODE_CLOSE_PUNCTUATION,
      G_UNICODE_FINAL_PUNCTUATION,
      G_UNICODE_INITIAL_PUNCTUATION,
      G_UNICODE_OTHER_PUNCTUATION,
      G_UNICODE_OPEN_PUNCTUATION,
      G_UNICODE_CURRENCY_SYMBOL,
      G_UNICODE_MODIFIER_SYMBOL,
      G_UNICODE_MATH_SYMBOL,
      G_UNICODE_OTHER_SYMBOL,
      G_UNICODE_LINE_SEPARATOR,
      G_UNICODE_PARAGRAPH_SEPARATOR,
      G_UNICODE_SPACE_SEPARATOR
    } GUnicodeType;

These are the possible character classifications. See http://www.unicode.org/Public/UNIDATA/UnicodeData.html.

### g_unichar_type ()

    GUnicodeType g_unichar_type                 (gunichar c);

Classifies a Unicode character by type.

`c` : | a Unicode character
Returns : | the type of the character.

### enum GUnicodeBreakType

    typedef enum
    {
      G_UNICODE_BREAK_MANDATORY,
      G_UNICODE_BREAK_CARRIAGE_RETURN,
      G_UNICODE_BREAK_LINE_FEED,
      G_UNICODE_BREAK_COMBINING_MARK,
      G_UNICODE_BREAK_SURROGATE,
      G_UNICODE_BREAK_ZERO_WIDTH_SPACE,
      G_UNICODE_BREAK_INSEPARABLE,
      G_UNICODE_BREAK_NON_BREAKING_GLUE,
      G_UNICODE_BREAK_CONTINGENT,
      G_UNICODE_BREAK_SPACE,
      G_UNICODE_BREAK_AFTER,
      G_UNICODE_BREAK_BEFORE,
      G_UNICODE_BREAK_BEFORE_AND_AFTER,
      G_UNICODE_BREAK_HYPHEN,
      G_UNICODE_BREAK_NON_STARTER,
      G_UNICODE_BREAK_OPEN_PUNCTUATION,
      G_UNICODE_BREAK_CLOSE_PUNCTUATION,
      G_UNICODE_BREAK_QUOTATION,
      G_UNICODE_BREAK_EXCLAMATION,
      G_UNICODE_BREAK_IDEOGRAPHIC,
      G_UNICODE_BREAK_NUMERIC,
      G_UNICODE_BREAK_INFIX_SEPARATOR,
      G_UNICODE_BREAK_SYMBOL,
      G_UNICODE_BREAK_ALPHABETIC,
      G_UNICODE_BREAK_PREFIX,
      G_UNICODE_BREAK_POSTFIX,
      G_UNICODE_BREAK_COMPLEX_CONTEXT,
      G_UNICODE_BREAK_AMBIGUOUS,
      G_UNICODE_BREAK_UNKNOWN,
      G_UNICODE_BREAK_NEXT_LINE,
      G_UNICODE_BREAK_WORD_JOINER,
      G_UNICODE_BREAK_HANGUL_L_JAMO,
      G_UNICODE_BREAK_HANGUL_V_JAMO,
      G_UNICODE_BREAK_HANGUL_T_JAMO,
      G_UNICODE_BREAK_HANGUL_LV_SYLLABLE,
      G_UNICODE_BREAK_HANGUL_LVT_SYLLABLE
    } GUnicodeBreakType;

These are the possible line break classifications. GLib 2.8 supports Unicode 4.0, GLib 2.10 supports Unicode 4.1. The five Hangul types were added in Unicode 4.1, so, has been introduced in GLib 2.10. Note that new types may be added in the future. Applications should be ready to handle unknown values. They may be regarded as `G_UNICODE_BREAK_UNKNOWN` See http://www.unicode.org/unicode/reports/tr14/.

### g_unichar_break_type ()

    GUnicodeBreakType g_unichar_break_type      (gunichar c);

Determines the break type of `c`. `c` should be a Unicode character (to derive a character from UTF-8 encoded text, use `g_utf8_get_char()`). The break type is used to find word and line breaks ("text boundaries"), Pango implements the Unicode boundary resolution algorithms and normally you would use a function such as `pango_break()` instead of caring about break types yourself.

`c` : | a Unicode character
Returns : | the break type of `c`

### g_unicode_canonical_ordering ()

    void        g_unicode_canonical_ordering    (gunichar *string,
                                                 gsize len);

Computes the canonical ordering of a string in-place. This rearranges decomposed characters in the string according to their combining classes. See the Unicode manual for more information.

`string` : | a UCS-4 encoded string.
`len` : | the maximum length of `string` to use.

### g_unicode_canonical_decomposition ()

    gunichar*   g_unicode_canonical_decomposition
                                                (gunichar ch,
                                                 gsize *result_len);

Computes the canonical decomposition of a Unicode character.

`ch` : | a Unicode character.
`result_len` : | location to store the length of the return value.
Returns : | a newly allocated string of Unicode characters. `result_len` is set to the resulting length of the string.

### g_unichar_get_mirror_char ()

    gboolean    g_unichar_get_mirror_char       (gunichar ch,
                                                 gunichar *mirrored_ch);

In Unicode, some characters are mirrored. This means that their images are mirrored horizontally in text that is laid out from right to left. For instance, "(" would become its mirror image, ")", in right-to-left text.

If `ch` has the Unicode mirrored property and there is another unicode character that typically has a glyph that is the mirror image of `ch`'s glyph and `mirrored_ch` is set, it puts that character in the address pointed to by `mirrored_ch`. Otherwise the original character is put.

`ch` : | a Unicode character
`mirrored_ch` : | location to store the mirrored character
Returns : | `TRUE` if `ch` has a mirrored character, `FALSE` otherwise

Since 2.4

### g_utf8_next_char()

    #define     g_utf8_next_char(p)

Skips to the next character in a UTF-8 string. The string must be valid; this macro is as fast as possible, and has no error-checking. You would use this macro to iterate over a string character by character. The macro returns the start of the next UTF-8 character. Before using this macro, use `g_utf8_validate()` to validate strings that may contain invalid UTF-8.

`p` : | Pointer to the start of a valid UTF-8 character.

### g_utf8_get_char ()

    gunichar    g_utf8_get_char                 (const gchar *p);

Converts a sequence of bytes encoded as UTF-8 to a Unicode character. If `p` does not point to a valid UTF-8 encoded character, results are undefined. If you are not sure that the bytes are complete valid Unicode characters, you should use `g_utf8_get_char_validated()` instead.

`p` : | a pointer to Unicode character encoded as UTF-8
Returns : | the resulting character

### g_utf8_get_char_validated ()

    gunichar    g_utf8_get_char_validated       (const  gchar *p,
                                                 gssize max_len);

Convert a sequence of bytes encoded as UTF-8 to a Unicode character. This function checks for incomplete characters, for invalid characters such as characters that are out of the range of Unicode, and for overlong encodings of valid characters.

`p` : | a pointer to Unicode character encoded as UTF-8
`max_len` : | the maximum number of bytes to read, or -1, for no maximum.
Returns : | the resulting character. If `p` points to a partial sequence at the end of a string that could begin a valid character, returns (gunichar)-2; otherwise, if `p` does not point to a valid UTF-8 encoded Unicode character, returns (gunichar)-1.

### g_utf8_offset_to_pointer ()

    gchar*      g_utf8_offset_to_pointer        (const gchar *str,
                                                 glong offset);

Converts from an integer character offset to a pointer to a position within the string.

Since 2.10, this function allows to pass a negative `offset` to step backwards. It is usually worth stepping backwards from the end instead of forwards if `offset` is in the last fourth of the string, since moving forward is about 3 times faster than moving backward.

`str` : | a UTF-8 encoded string
`offset` : | a character offset within `str`
Returns : | the resulting pointer

### g_utf8_pointer_to_offset ()

    glong       g_utf8_pointer_to_offset        (const gchar *str,
                                                 const gchar *pos);

Converts from a pointer to position within a string to a integer character offset.

Since 2.10, this function allows `pos` to be before `str`, and returns a negative offset in this case.

`str` : | a UTF-8 encoded string
`pos` : | a pointer to a position within `str`
Returns : | the resulting character offset

### g_utf8_prev_char ()

    gchar*      g_utf8_prev_char                (const gchar *p);

Finds the previous UTF-8 character in the string before `p`.

`p` does not have to be at the beginning of a UTF-8 character. No check is made to see if the character found is actually valid other than it starts with an appropriate byte. If `p` might be the first character of the string, you must use `g_utf8_find_prev_char()` instead.

`p` : | a pointer to a position within a UTF-8 encoded string
Returns : | a pointer to the found character.

### g_utf8_find_next_char ()

    gchar*      g_utf8_find_next_char           (const gchar *p,
                                                 const gchar *end);

Finds the start of the next UTF-8 character in the string after `p`.

`p` does not have to be at the beginning of a UTF-8 character. No check is made to see if the character found is actually valid other than it starts with an appropriate byte.

`p` : | a pointer to a position within a UTF-8 encoded string
`end` : | a pointer to the end of the string, or `NULL` to indicate that the string is nul-terminated, in which case the returned value will be
Returns : | a pointer to the found character or `NULL`

### g_utf8_find_prev_char ()

    gchar*      g_utf8_find_prev_char           (const gchar *str,
                                                 const gchar *p);

Given a position `p` with a UTF-8 encoded string `str`, find the start of the previous UTF-8 character starting before `p`. Returns `NULL` if no UTF-8 characters are present in `str` before `p`.

`p` does not have to be at the beginning of a UTF-8 character. No check is made to see if the character found is actually valid other than it starts with an appropriate byte.

`str` : | pointer to the beginning of a UTF-8 encoded string
`p` : | pointer to some position within `str`
Returns : | a pointer to the found character or `NULL`.

### g_utf8_strlen ()

    glong       g_utf8_strlen                   (const gchar *p,
                                                 gssize max);

Returns the length of the string in characters.

`p` : | pointer to the start of a UTF-8 encoded string.
`max` : | the maximum number of bytes to examine. If `max` is less than 0, then the string is assumed to be nul-terminated. If `max` is 0, `p` will not be examined and may be `NULL`.
Returns : | the length of the string in characters

### g_utf8_strncpy ()

    gchar*      g_utf8_strncpy                  (gchar *dest,
                                                 const gchar *src,
                                                 gsize n);

Like the standard C `strncpy()` function, but copies a given number of characters instead of a given number of bytes. The `src` string must be valid UTF-8 encoded text. (Use `g_utf8_validate()` on all text before trying to use UTF-8 utility functions with it.)

`dest` : | buffer to fill with characters from `src`
`src` : | UTF-8 encoded string
`n` : | character count
Returns : | `dest`

### g_utf8_strchr ()

    gchar*      g_utf8_strchr                   (const gchar *p,
                                                 gssize len,
                                                 gunichar c);

Finds the leftmost occurrence of the given Unicode character in a UTF-8 encoded string, while limiting the search to `len` bytes. If `len` is -1, allow unbounded search.

`p` : | a nul-terminated UTF-8 encoded string
`len` : | the maximum length of `p`
`c` : | a Unicode character
Returns : | `NULL` if the string does not contain the character, otherwise, a pointer to the start of the leftmost occurrence of the character in the string.

### g_utf8_strrchr ()

    gchar*      g_utf8_strrchr                  (const gchar *p,
                                                 gssize len,
                                                 gunichar c);

Find the rightmost occurrence of the given Unicode character in a UTF-8 encoded string, while limiting the search to `len` bytes. If `len` is -1, allow unbounded search.

`p` : | a nul-terminated UTF-8 encoded string
`len` : | the maximum length of `p`
`c` : | a Unicode character
Returns : | `NULL` if the string does not contain the character, otherwise, a pointer to the start of the rightmost occurrence of the character in the string.

### g_utf8_strreverse ()

    gchar*      g_utf8_strreverse               (const gchar *str,
                                                 gssize len);

Reverses a UTF-8 string. `str` must be valid UTF-8 encoded text. (Use `g_utf8_validate()` on all text before trying to use UTF-8 utility functions with it.)

Note that unlike `g_strreverse()`, this function returns newly-allocated memory, which should be freed with `g_free()` when no longer needed.

`str` : | a UTF-8 encoded string
`len` : | the maximum length of `str` to use. If `len` < 0, then the string is nul-terminated.
Returns : | a newly-allocated string which is the reverse of `str`.

Since 2.2

### g_utf8_validate ()

    gboolean    g_utf8_validate                 (const gchar *str,
                                                 gssize max_len,
                                                 const gchar **end);

Validates UTF-8 encoded text. `str` is the text to validate; if `str` is nul-terminated, then `max_len` can be -1, otherwise `max_len` should be the number of bytes to validate. If `end` is non-`NULL`, then the end of the valid range will be stored there (i.e. the start of the first invalid character if some bytes were invalid, or the end of the text being validated otherwise).

Note that `g_utf8_validate()` returns `FALSE` if `max_len` is positive and NUL is met before `max_len` bytes have been read.

Returns `TRUE` if all of `str` was valid. Many GLib and GTK+ routines require valid UTF-8 as input; so data read from a file or the network should be checked with `g_utf8_validate()` before doing anything else with it.

`str` : | a pointer to character data
`max_len` : | max bytes to validate, or -1 to go until NUL
`end` : | return location for end of valid data
Returns : | `TRUE` if the text was valid UTF-8

### g_utf8_strup ()

    gchar*      g_utf8_strup                    (const gchar *str,
                                                 gssize len);

Converts all Unicode characters in the string that have a case to uppercase. The exact manner that this is done depends on the current locale, and may result in the number of characters in the string increasing. (For instance, the German ess-zet will be changed to SS.)

`str` : | a UTF-8 encoded string
`len` : | length of `str`, in bytes, or -1 if `str` is nul-terminated.
Returns : | a newly allocated string, with all characters converted to uppercase.

### g_utf8_strdown ()

    gchar*      g_utf8_strdown                  (const gchar *str,
                                                 gssize len);

Converts all Unicode characters in the string that have a case to lowercase. The exact manner that this is done depends on the current locale, and may result in the number of characters in the string changing.

`str` : | a UTF-8 encoded string
`len` : | length of `str`, in bytes, or -1 if `str` is nul-terminated.
Returns : | a newly allocated string, with all characters converted to lowercase.

### g_utf8_casefold ()

    gchar*      g_utf8_casefold                 (const gchar *str,
                                                 gssize len);

Converts a string into a form that is independent of case. The result will not correspond to any particular case, but can be compared for equality or ordered with the results of calling `g_utf8_casefold()` on other strings.

Note that calling `g_utf8_casefold()` followed by `g_utf8_collate()` is only an approximation to the correct linguistic case insensitive ordering, though it is a fairly good one. Getting this exactly right would require a more sophisticated collation function that takes case sensitivity into account. GLib does not currently provide such a function.

`str` : | a UTF-8 encoded string
`len` : | length of `str`, in bytes, or -1 if `str` is nul-terminated.
Returns : | a newly allocated string, that is a case independent form of `str`.

### g_utf8_normalize ()

    gchar*      g_utf8_normalize                (const gchar *str,
                                                 gssize len,
                                                 GNormalizeMode mode);

Converts a string into canonical form, standardizing such issues as whether a character with an accent is represented as a base character and combining accent or as a single precomposed character. You should generally call `g_utf8_normalize()` before comparing two Unicode strings.

The normalization mode `G_NORMALIZE_DEFAULT` only standardizes differences that do not affect the text content, such as the above-mentioned accent representation. `G_NORMALIZE_ALL` also standardizes the "compatibility" characters in Unicode, such as SUPERSCRIPT THREE to the standard forms (in this case DIGIT THREE). Formatting information may be lost but for most text operations such characters should be considered the same. For example, `g_utf8_collate()` normalizes with `G_NORMALIZE_ALL` as its first step.

`G_NORMALIZE_DEFAULT_COMPOSE` and `G_NORMALIZE_ALL_COMPOSE` are like `G_NORMALIZE_DEFAULT` and `G_NORMALIZE_ALL`, but returned a result with composed forms rather than a maximally decomposed form. This is often useful if you intend to convert the string to a legacy encoding or pass it to a system with less capable Unicode handling.

`str` : | a UTF-8 encoded string.
`len` : | length of `str`, in bytes, or -1 if `str` is nul-terminated.
`mode` : | the type of normalization to perform.
Returns : | a newly allocated string, that is the normalized form of `str`.

### enum GNormalizeMode

    typedef enum {
      G_NORMALIZE_DEFAULT,
      G_NORMALIZE_NFD = G_NORMALIZE_DEFAULT,
      G_NORMALIZE_DEFAULT_COMPOSE,
      G_NORMALIZE_NFC = G_NORMALIZE_DEFAULT_COMPOSE,
      G_NORMALIZE_ALL,
      G_NORMALIZE_NFKD = G_NORMALIZE_ALL,
      G_NORMALIZE_ALL_COMPOSE,
      G_NORMALIZE_NFKC = G_NORMALIZE_ALL_COMPOSE
    } GNormalizeMode;

Defines how a Unicode string is transformed in a canonical form, standardizing such issues as whether a character with an accent is represented as a base character and combining accent or as a single precomposed character. Unicode strings should generally be normalized before comparing them.

`G_NORMALIZE_DEFAULT` | standardize differences that do not affect the text content, such as the above-mentioned accent representation.
`G_NORMALIZE_NFD` | another name for `G_NORMALIZE_DEFAULT`.
`G_NORMALIZE_DEFAULT_COMPOSE` | like `G_NORMALIZE_DEFAULT`, but with composed forms rather than a maximally decomposed form.
`G_NORMALIZE_NFC` | another name for `G_NORMALIZE_DEFAULT_COMPOSE`.
`G_NORMALIZE_ALL` | beyond `G_NORMALIZE_DEFAULT` also standardize the "compatibility" characters in Unicode, such as SUPERSCRIPT THREE to the standard forms (in this case DIGIT THREE). Formatting information may be lost but for most text operations such characters should be considered the same.
`G_NORMALIZE_NFKD` | another name for `G_NORMALIZE_ALL`.
`G_NORMALIZE_ALL_COMPOSE` | like `G_NORMALIZE_ALL`, but with composed forms rather than a maximally decomposed form.
`G_NORMALIZE_NFKC` | another name for `G_NORMALIZE_ALL_COMPOSE`.

### g_utf8_collate ()

    gint        g_utf8_collate                  (const gchar *str1,
                                                 const gchar *str2);

Compares two strings for ordering using the linguistically correct rules for the current locale. When sorting a large number of strings, it will be significantly faster to obtain collation keys with `g_utf8_collate_key()` and compare the keys with `strcmp()` when sorting instead of sorting the original strings.

`str1` : | a UTF-8 encoded string
`str2` : | a UTF-8 encoded string
Returns : | < 0 if `str1` compares before `str2`, 0 if they compare equal, > 0 if `str1` compares after `str2`.

### g_utf8_collate_key ()

    gchar*      g_utf8_collate_key              (const gchar *str,
                                                 gssize len);

Converts a string into a collation key that can be compared with other collation keys produced by the same function using `strcmp()`. The results of comparing the collation keys of two strings with `strcmp()` will always be the same as comparing the two original keys with `g_utf8_collate()`.

`str` : | a UTF-8 encoded string.
`len` : | length of `str`, in bytes, or -1 if `str` is nul-terminated.
Returns : | a newly allocated string. This string should be freed with `g_free()` when you are done with it.

### g_utf8_collate_key_for_filename ()

    gchar*      g_utf8_collate_key_for_filename (const gchar *str,
                                                 gssize len);

Converts a string into a collation key that can be compared with other collation keys produced by the same function using `strcmp()`.

In order to sort filenames correctly, this function treats the dot '.' as a special case. Most dictionary orderings seem to consider it insignificant, thus producing the ordering "event.c" "eventgenerator.c" "event.h" instead of "event.c" "event.h" "eventgenerator.c". Also, we would like to treat numbers intelligently so that "file1" "file10" "file5" is sorted as "file1" "file5" "file10".

`str` : | a UTF-8 encoded string.
`len` : | length of `str`, in bytes, or -1 if `str` is nul-terminated.
Returns : | a newly allocated string. This string should be freed with `g_free()` when you are done with it.

Since 2.8

### g_utf8_to_utf16 ()

    gunichar2*  g_utf8_to_utf16                 (const gchar *str,
                                                 glong len,
                                                 glong *items_read,
                                                 glong *items_written,
                                                 GError **error);

Convert a string from UTF-8 to UTF-16. A 0 character will be added to the result after the converted text.

`str` : | a UTF-8 encoded string
`len` : | the maximum length (number of characters) of `str` to use. If `len` < 0, then the string is nul-terminated.
`items_read` : | location to store number of bytes read, or `NULL`. If `NULL`, then `G_CONVERT_ERROR_PARTIAL_INPUT` will be returned in case `str` contains a trailing partial character. If an error occurs then the index of the invalid input is stored here.
`items_written` : | location to store number of gunichar2 written, or `NULL`. The value stored here does not include the trailing 0.
`error` : | location to store the error occuring, or `NULL` to ignore errors. Any of the errors in GConvertError other than `G_CONVERT_ERROR_NO_CONVERSION` may occur.
Returns : | a pointer to a newly allocated UTF-16 string. This value must be freed with `g_free()`. If an error occurs, `NULL` will be returned and `error` set.

### g_utf8_to_ucs4 ()

    gunichar*   g_utf8_to_ucs4                  (const gchar *str,
                                                 glong len,
                                                 glong *items_read,
                                                 glong *items_written,
                                                 GError **error);

Convert a string from UTF-8 to a 32-bit fixed width representation as UCS-4. A trailing 0 will be added to the string after the converted text.

`str` : | a UTF-8 encoded string
`len` : | the maximum length of `str` to use. If `len` < 0, then the string is nul-terminated.
`items_read` : | location to store number of bytes read, or `NULL`. If `NULL`, then `G_CONVERT_ERROR_PARTIAL_INPUT` will be returned in case `str` contains a trailing partial character. If an error occurs then the index of the invalid input is stored here.
`items_written` : | location to store number of characters written or `NULL`. The value here stored does not include the trailing 0 character.
`error` : | location to store the error occuring, or `NULL` to ignore errors. Any of the errors in GConvertError other than `G_CONVERT_ERROR_NO_CONVERSION` may occur.
Returns : | a pointer to a newly allocated UCS-4 string. This value must be freed with `g_free()`. If an error occurs, `NULL` will be returned and `error` set.

### g_utf8_to_ucs4_fast ()

    gunichar*   g_utf8_to_ucs4_fast             (const gchar *str,
                                                 glong len,
                                                 glong *items_written);

Convert a string from UTF-8 to a 32-bit fixed width representation as UCS-4, assuming valid UTF-8 input. This function is roughly twice as fast as `g_utf8_to_ucs4()` but does no error checking on the input.

`str` : | a UTF-8 encoded string
`len` : | the maximum length of `str` to use. If `len` < 0, then the string is nul-terminated.
`items_written` : | location to store the number of characters in the result, or `NULL`.
Returns : | a pointer to a newly allocated UCS-4 string. This value must be freed with `g_free()`.

### g_utf16_to_ucs4 ()

    gunichar*   g_utf16_to_ucs4                 (const gunichar2 *str,
                                                 glong len,
                                                 glong *items_read,
                                                 glong *items_written,
                                                 GError **error);

Convert a string from UTF-16 to UCS-4. The result will be terminated with a 0 character.

`str` : | a UTF-16 encoded string
`len` : | the maximum length (number of gunichar2) of `str` to use. If `len` < 0, then the string is terminated with a 0 character.
`items_read` : | location to store number of words read, or `NULL`. If `NULL`, then `G_CONVERT_ERROR_PARTIAL_INPUT` will be returned in case `str` contains a trailing partial character. If an error occurs then the index of the invalid input is stored here.
`items_written` : | location to store number of characters written, or `NULL`. The value stored here does not include the trailing 0 character.
`error` : | location to store the error occuring, or `NULL` to ignore errors. Any of the errors in GConvertError other than `G_CONVERT_ERROR_NO_CONVERSION` may occur.
Returns : | a pointer to a newly allocated UCS-4 string. This value must be freed with `g_free()`. If an error occurs, `NULL` will be returned and `error` set.

### g_utf16_to_utf8 ()

    gchar*      g_utf16_to_utf8                 (const gunichar2 *str,
                                                 glong len,
                                                 glong *items_read,
                                                 glong *items_written,
                                                 GError **error);

Convert a string from UTF-16 to UTF-8. The result will be terminated with a 0 byte.

Note that the input is expected to be already in native endianness, an initial byte-order-mark character is not handled specially. `g_convert()` can be used to convert a byte buffer of UTF-16 data of ambiguous endianess.

`str` : | a UTF-16 encoded string
`len` : | the maximum length (number of gunichar2) of `str` to use. If `len` < 0, then the string is terminated with a 0 character.
`items_read` : | location to store number of words read, or `NULL`. If `NULL`, then `G_CONVERT_ERROR_PARTIAL_INPUT` will be returned in case `str` contains a trailing partial character. If an error occurs then the index of the invalid input is stored here.
`items_written` : | location to store number of bytes written, or `NULL`. The value stored here does not include the trailing 0 byte.
`error` : | location to store the error occuring, or `NULL` to ignore errors. Any of the errors in GConvertError other than `G_CONVERT_ERROR_NO_CONVERSION` may occur.
Returns : | a pointer to a newly allocated UTF-8 string. This value must be freed with `g_free()`. If an error occurs, `NULL` will be returned and `error` set.

### g_ucs4_to_utf16 ()

    gunichar2*  g_ucs4_to_utf16                 (const gunichar *str,
                                                 glong len,
                                                 glong *items_read,
                                                 glong *items_written,
                                                 GError **error);

Convert a string from UCS-4 to UTF-16. A 0 character will be added to the result after the converted text.

`str` : | a UCS-4 encoded string
`len` : | the maximum length (number of characters) of `str` to use. If `len` < 0, then the string is terminated with a 0 character.
`items_read` : | location to store number of bytes read, or `NULL`. If an error occurs then the index of the invalid input is stored here.
`items_written` : | location to store number of gunichar2 written, or `NULL`. The value stored here does not include the trailing 0.
`error` : | location to store the error occuring, or `NULL` to ignore errors. Any of the errors in GConvertError other than `G_CONVERT_ERROR_NO_CONVERSION` may occur.
Returns : | a pointer to a newly allocated UTF-16 string. This value must be freed with `g_free()`. If an error occurs, `NULL` will be returned and `error` set.

### g_ucs4_to_utf8 ()

    gchar*      g_ucs4_to_utf8                  (const gunichar *str,
                                                 glong len,
                                                 glong *items_read,
                                                 glong *items_written,
                                                 GError **error);

Convert a string from a 32-bit fixed width representation as UCS-4. to UTF-8. The result will be terminated with a 0 byte.

`str` : | a UCS-4 encoded string
`len` : | the maximum length (number of characters) of `str` to use. If `len` < 0, then the string is terminated with a 0 character.
`items_read` : | location to store number of characters read, or `NULL`.
`items_written` : | location to store number of bytes written or `NULL`. The value here stored does not include the trailing 0 byte.
`error` : | location to store the error occuring, or `NULL` to ignore errors. Any of the errors in GConvertError other than `G_CONVERT_ERROR_NO_CONVERSION` may occur.
Returns : | a pointer to a newly allocated UTF-8 string. This value must be freed with `g_free()`. If an error occurs, `NULL` will be returned and `error` set. In that case, `items_read` will be set to the position of the first invalid input character.

### g_unichar_to_utf8 ()

    gint        g_unichar_to_utf8               (gunichar c,
                                                 gchar *outbuf);

Converts a single character to UTF-8.

`c` : | a Unicode character code
`outbuf` : | output buffer, must have at least 6 bytes of space. If `NULL`, the length will be computed and returned and nothing will be written to `outbuf`.
Returns : | number of bytes written

## See Also

`g_locale_to_utf8()`, `g_locale_from_utf8()` | Convenience functions for converting between UTF-8 and the locale encoding.

[3] surrogate pairs