Miscellaneous Utility Functions

Miscellaneous Utility Functions — a selection of portable utility functions.

Synopsis


#include <glib.h>


G_CONST_RETURN gchar* g_get_application_name
                                            (void);
void        g_set_application_name          (const gchar *application_name);
gchar*      g_get_prgname                   (void);
void        g_set_prgname                   (const gchar *prgname);
G_CONST_RETURN gchar* g_getenv              (const gchar *variable);
gboolean    g_setenv                        (const gchar *variable,
                                             const gchar *value,
                                             gboolean overwrite);
void        g_unsetenv                      (const gchar *variable);
G_CONST_RETURN gchar* g_get_user_name       (void);
G_CONST_RETURN gchar* g_get_real_name       (void);

G_CONST_RETURN gchar* g_get_home_dir        (void);
G_CONST_RETURN gchar* g_get_tmp_dir         (void);
gchar*      g_get_current_dir               (void);
G_CONST_RETURN gchar* g_basename            (const gchar *file_name);
#define     g_dirname
gboolean    g_path_is_absolute              (const gchar *file_name);
G_CONST_RETURN gchar* g_path_skip_root      (const gchar *file_name);
gchar*      g_path_get_basename             (const gchar *file_name);
gchar*      g_path_get_dirname              (const gchar *file_name);
gchar*      g_build_filename                (const gchar *first_element,
                                             ...);
gchar*      g_build_path                    (const gchar *separator,
                                             const gchar *first_element,
                                             ...);

gchar*      g_find_program_in_path          (const gchar *program);

gint        g_bit_nth_lsf                   (gulong mask,
                                             gint nth_bit);
gint        g_bit_nth_msf                   (gulong mask,
                                             gint nth_bit);
guint       g_bit_storage                   (gulong number);

guint       g_spaced_primes_closest         (guint num);

void        g_atexit                        (GVoidFunc func);

guint       g_parse_debug_string            (const gchar *string,
                                             const GDebugKey *keys,
                                             guint nkeys);
struct      GDebugKey;

void        (*GVoidFunc)                    (void);
void        (*GFreeFunc)                    (gpointer data);

void        g_qsort_with_data               (gconstpointer pbase,
                                             gint total_elems,
                                             gsize size,
                                             GCompareDataFunc compare_func,
                                             gpointer user_data);

void        g_nullify_pointer               (gpointer *nullify_location);

Description

These are portable utility functions.

Details

g_get_application_name ()

G_CONST_RETURN gchar* g_get_application_name
                                            (void);

Gets a human-readable name for the application, as set by g_set_application_name(). This name should be localized if possible, and is intended for display to the user. Contrast with g_get_prgname(), which gets a non-localized name. If g_set_application_name() has not been called, returns the result of g_get_prgname() (which may be NULL if g_set_prgname() has also not been called).

Returns : human-readable application name. may return NULL

Since 2.2


g_set_application_name ()

void        g_set_application_name          (const gchar *application_name);

Sets a human-readable name for the application. This name should be localized if possible, and is intended for display to the user. Contrast with g_set_prgname(), which sets a non-localized name. g_set_prgname() will be called automatically by gtk_init(), but g_set_application_name() will not.

Note that for thread safety reasons, this function can only be called once.

The application name will be used in contexts such as error messages, or when displaying an application's name in the task list.

application_name : localized name of the application

g_get_prgname ()

gchar*      g_get_prgname                   (void);

Gets the name of the program. This name should NOT be localized, contrast with g_get_application_name(). (If you are using GDK or GTK+ the program name is set in gdk_init(), which is called by gtk_init(). The program name is found by taking the last component of argv[0].)

Returns :the name of the program.

g_set_prgname ()

void        g_set_prgname                   (const gchar *prgname);

Sets the name of the program. This name should NOT be localized, contrast with g_set_application_name(). Note that for thread-safety reasons this function can only be called once.

prgname :the name of the program.

g_getenv ()

G_CONST_RETURN gchar* g_getenv              (const gchar *variable);

Returns an environment variable.

variable : the environment variable to get.
Returns : the value of the environment variable, or NULL if the environment variable is not found. The returned string may be overwritten by the next call to g_getenv(), g_setenv() or g_unsetenv().

g_setenv ()

gboolean    g_setenv                        (const gchar *variable,
                                             const gchar *value,
                                             gboolean overwrite);

Sets an environment variable.

Note that on some systems, the memory used for the variable and its value can't be reclaimed later.

variable : the environment variable to set, must not contain '='.
value : the value for to set the variable to.
overwrite : whether to change the variable if it already exists.
Returns : FALSE if the environment variable couldn't be set.

Since 2.4


g_unsetenv ()

void        g_unsetenv                      (const gchar *variable);

Removes an environment variable from the environment.

Note that on some systems, the memory used for the variable and its value can't be reclaimed. Furthermore, this function can't be guaranteed to operate in a threadsafe way.

variable : the environment variable to remove, must not contain '='.

Since 2.4


g_get_user_name ()

G_CONST_RETURN gchar* g_get_user_name       (void);

Gets the user name of the current user.

Returns :the user name of the current user.

g_get_real_name ()

G_CONST_RETURN gchar* g_get_real_name       (void);

Gets the real name of the user. This usually comes from the user's entry in the passwd file. The encoding of the returned string is system defined. If the real user name cannot be determined, the string "Unknown" is returned.

Returns :the user's real name.

g_get_home_dir ()

G_CONST_RETURN gchar* g_get_home_dir        (void);

Gets the current user's home directory.

Returns :the current user's home directory.

g_get_tmp_dir ()

G_CONST_RETURN gchar* g_get_tmp_dir         (void);

Gets the directory to use for temporary files. This is found from inspecting the environment variables TMPDIR, TMP, and TEMP in that order. If none of those are defined "/tmp" is returned on UNIX and "C:\" on Windows.

Returns :the directory to use for temporary files.

g_get_current_dir ()

gchar*      g_get_current_dir               (void);

Gets the current directory. The returned string should be freed when no longer needed.

Returns :the current directory.

g_basename ()

G_CONST_RETURN gchar* g_basename            (const gchar *file_name);

Warning

g_basename is deprecated and should not be used in newly-written code. Use g_path_get_basename() instead, but notice that g_path_get_basename() allocates new memory for the returned string, unlike this function which returns a pointer into the argument.

Gets the name of the file without any leading directory components. It returns a pointer into the given file name string.

file_name : the name of the file.
Returns : the name of the file without any leading directory components.

g_dirname

#define     g_dirname

Warning

g_dirname is deprecated and should not be used in newly-written code.

This function is deprecated and will be removed in the next major release of GLib. Use g_path_get_dirname() instead.

Gets the directory components of a file name. If the file name has no directory components "." is returned. The returned string should be freed when no longer needed.

Returns :the directory components of the file.

g_path_is_absolute ()

gboolean    g_path_is_absolute              (const gchar *file_name);

Returns TRUE if the given file_name is an absolute file name, i.e. it contains a full path from the root directory such as '/usr/local' on UNIX or 'C:\windows' on Windows systems.

file_name :a file name.
Returns :TRUE if file_name is an absolute path.

g_path_skip_root ()

G_CONST_RETURN gchar* g_path_skip_root      (const gchar *file_name);

Returns a pointer into file_name after the root component, i.e. after the '/' in UNIX or 'C:\' under Windows. If file_name is not an absolute path it returns NULL.

file_name :a file name.
Returns :a pointer into file_name after the root component.

g_path_get_basename ()

gchar*      g_path_get_basename             (const gchar *file_name);

Gets the last component of the filename. If file_name ends with a directory separator it gets the component before the last slash. If file_name consists only of directory separators (and on Windows, possibly a drive letter), a single separator is returned. If file_name is empty, it gets ".".

file_name : the name of the file.
Returns : a newly allocated string containing the last component of the filename.

g_path_get_dirname ()

gchar*      g_path_get_dirname              (const gchar *file_name);

Gets the directory components of a file name. If the file name has no directory components "." is returned. The returned string should be freed when no longer needed.

file_name :the name of the file.
Returns :the directory components of the file.

g_build_filename ()

gchar*      g_build_filename                (const gchar *first_element,
                                             ...);

Creates a filename from a series of elements using the correct separator for filenames.

On Unix, this function behaves identically to g_build_path (G_DIR_SEPARATOR_S, first_element, ....).

On Windows, it takes into account that either the backslash (\ or slash (/) can be used as separator in filenames, but otherwise behaves as on Unix. When file pathname separators need to be inserted, the one that last previously occurred in the parameters (reading from left to right) is used.

No attempt is made to force the resulting filename to be an absolute path. If the first element is a relative path, the result will be a relative path.

first_element : the first element in the path
... : remaining elements in path, terminated by NULL
Returns : a newly-allocated string that must be freed with g_free().

g_build_path ()

gchar*      g_build_path                    (const gchar *separator,
                                             const gchar *first_element,
                                             ...);

Creates a path from a series of elements using separator as the separator between elements. At the boundary between two elements, any trailing occurrences of separator in the first element, or leading occurrences of separator in the second element are removed and exactly one copy of the separator is inserted.

Empty elements are ignored.

The number of leading copies of the separator on the result is the same as the number of leading copies of the separator on the first non-empty element.

The number of trailing copies of the separator on the result is the same as the number of trailing copies of the separator on the last non-empty element. (Determination of the number of trailing copies is done without stripping leading copies, so if the separator is ABA, ABABA has 1 trailing copy.)

However, if there is only a single non-empty element, and there are no characters in that element not part of the leading or trailing separators, then the result is exactly the original value of that element.

Other than for determination of the number of leading and trailing copies of the separator, elements consisting only of copies of the separator are ignored.

separator : a string used to separator the elements of the path.
first_element : the first element in the path
... : remaining elements in path, terminated by NULL
Returns : a newly-allocated string that must be freed with g_free().

g_find_program_in_path ()

gchar*      g_find_program_in_path          (const gchar *program);

Locates the first executable named program in the user's path, in the same way that execvp() would locate it. Returns an allocated string with the absolute path name, or NULL if the program is not found in the path. If program is already an absolute path, returns a copy of program if program exists and is executable, and NULL otherwise.

On Windows, if program does not have a file type suffix, tries to append the suffixes in the PATHEXT environment variable (if that doesn't exists, the suffixes .com, .exe, and .bat) in turn, and then look for the resulting file name in the same way as CreateProcess() would. This means first in the directory where the program was loaded from, then in the current directory, then in the Windows 32-bit system directory, then in the Windows directory, and finally in the directories in the PATH environment variable. If the program is found, the return value contains the full name including the type suffix.

program : a program name
Returns : absolute path, or NULL

g_bit_nth_lsf ()

gint        g_bit_nth_lsf                   (gulong mask,
                                             gint nth_bit);

Find the position of the first bit set in mask, searching from (but not including) nth_bit upwards. Bits are numbered from 0 (least significant) to sizeof(gulong) * 8 - 1 (31 or 63, usually). To start searching from the 0th bit, set nth_bit to -1.

mask :a gulong containing flags.
nth_bit :the index of the bit to start the search from.
Returns :the index of the first bit set which is higher than nth_bit.

g_bit_nth_msf ()

gint        g_bit_nth_msf                   (gulong mask,
                                             gint nth_bit);

Find the position of the first bit set in mask, searching from (but not including) nth_bit downwards. Bits are numbered from 0 (least significant) to sizeof(gulong) * 8 - 1 (31 or 63, usually). To start searching from the last bit, set nth_bit to -1 or GLIB_SIZEOF_LONG * 8.

mask :a gulong containing flags.
nth_bit :the index of the bit to start the search from.
Returns :the index of the first bit set which is lower than nth_bit.

g_bit_storage ()

guint       g_bit_storage                   (gulong number);

Gets the number of bits used to hold number, e.g. if number is 4, 3 bits are needed.

number :a guint.
Returns :the number of bits used to hold number.

g_spaced_primes_closest ()

guint       g_spaced_primes_closest         (guint num);

Gets the smallest prime number from a built-in array of primes which is larger than num. This is used within GLib to calculate the optimum size of a GHashTable.

The built-in array of primes ranges from 11 to 13845163 such that each prime is approximately 1.5-2 times the previous prime.

num :a guint.
Returns :the smallest prime number from a built-in array of primes which is larger than num.

g_atexit ()

void        g_atexit                        (GVoidFunc func);

Specifies a function to be called at normal program termination.

func :the function to call on normal program termination.

g_parse_debug_string ()

guint       g_parse_debug_string            (const gchar *string,
                                             const GDebugKey *keys,
                                             guint nkeys);

Parses a string containing debugging options separated by ':' into a guint containing bit flags. This is used within GDK and GTK+ to parse the debug options passed on the command line or through environment variables.

string :a list of debug options separated by ':' or "all" to set all flags.
keys :pointer to an array of GDebugKey which associate strings with bit flags.
nkeys :the number of GDebugKey in the array.
Returns :the combined set of bit flags.

struct GDebugKey

struct GDebugKey {

  gchar *key;
  guint	 value;
};

Associates a string with a bit flag. Used in g_parse_debug_string().


GVoidFunc ()

void        (*GVoidFunc)                    (void);

Declares a type of function which takes no arguments and has no return value. It is used to specify the type function passed to g_atexit().


GFreeFunc ()

void        (*GFreeFunc)                    (gpointer data);

Declares a type of function which takes an arbitrary data pointer argument and has no return value. It is not currently used in GLib or GTK+.

data :a data pointer.

g_qsort_with_data ()

void        g_qsort_with_data               (gconstpointer pbase,
                                             gint total_elems,
                                             gsize size,
                                             GCompareDataFunc compare_func,
                                             gpointer user_data);

This is just like the standard C qsort() function, but the comparison routine accepts a user data argument.

pbase : start of array to sort
total_elems : elements in the array
size : size of each element
compare_func : function to compare elements
user_data : data to pass to compare_func

g_nullify_pointer ()

void        g_nullify_pointer               (gpointer *nullify_location);

Set the pointer at the specified location to NULL.

nullify_location : the memory address of the pointer.