g_new()

#define             g_new(struct_type, n_structs)

Allocates n_structs elements of type struct_type . The returned pointer is cast to a pointer to the given type. If n_structs is 0 it returns NULL. Care is taken to avoid overflow when calculating the size of the allocated block.

Since the returned pointer is already casted to the right type, it is normally unnecessary to cast it explicitly, and doing so might hide memory allocation errors.

g_new0()

#define             g_new0(struct_type, n_structs)

Allocates n_structs elements of type struct_type , initialized to 0's. The returned pointer is cast to a pointer to the given type. If n_structs is 0 it returns NULL. Care is taken to avoid overflow when calculating the size of the allocated block.

Since the returned pointer is already casted to the right type, it is normally unnecessary to cast it explicitly, and doing so might hide memory allocation errors.

g_renew()

#define             g_renew(struct_type, mem, n_structs)

Reallocates the memory pointed to by mem , so that it now has space for n_structs elements of type struct_type . It returns the new address of the memory, which may have been moved. Care is taken to avoid overflow when calculating the size of the allocated block.

g_try_new()

#define             g_try_new(struct_type, n_structs)

Attempts to allocate n_structs elements of type struct_type , and returns NULL on failure. Contrast with g_new(), which aborts the program on failure. The returned pointer is cast to a pointer to the given type. The function returns NULL when n_structs is 0 of if an overflow occurs.

Since 2.8

g_try_new0()

#define             g_try_new0(struct_type, n_structs)

Attempts to allocate n_structs elements of type struct_type , initialized to 0's, and returns NULL on failure. Contrast with g_new0(), which aborts the program on failure. The returned pointer is cast to a pointer to the given type. The function returns NULL when n_structs is 0 of if an overflow occurs.

Since 2.8

g_try_renew()

#define             g_try_renew(struct_type, mem, n_structs)

Attempts to reallocate the memory pointed to by mem , so that it now has space for n_structs elements of type struct_type , and returns NULL on failure. Contrast with g_renew(), which aborts the program on failure. It returns the new address of the memory, which may have been moved. The function returns NULL if an overflow occurs.

Since 2.8

g_malloc ()

gpointer
g_malloc (gsize n_bytes);

Allocates n_bytes bytes of memory. If n_bytes is 0 it returns NULL.

g_malloc0 ()

gpointer
g_malloc0 (gsize n_bytes);

Allocates n_bytes bytes of memory, initialized to 0's. If n_bytes is 0 it returns NULL.

g_realloc ()

gpointer
g_realloc (gpointer mem,
           gsize n_bytes);

Reallocates the memory pointed to by mem , so that it now has space for n_bytes bytes of memory. It returns the new address of the memory, which may have been moved. mem may be NULL, in which case it's considered to have zero-length. n_bytes may be 0, in which case NULL will be returned and mem will be freed unless it is NULL.

g_try_malloc ()

gpointer
g_try_malloc (gsize n_bytes);

Attempts to allocate n_bytes , and returns NULL on failure. Contrast with g_malloc(), which aborts the program on failure.

g_try_malloc0 ()

gpointer
g_try_malloc0 (gsize n_bytes);

Attempts to allocate n_bytes , initialized to 0's, and returns NULL on failure. Contrast with g_malloc0(), which aborts the program on failure.

Since 2.8

g_try_realloc ()

gpointer
g_try_realloc (gpointer mem,
               gsize n_bytes);

Attempts to realloc mem to a new size, n_bytes , and returns NULL on failure. Contrast with g_realloc(), which aborts the program on failure. If mem is NULL, behaves the same as g_try_malloc().

g_malloc_n ()

gpointer
g_malloc_n (gsize n_blocks,
            gsize n_block_bytes);

This function is similar to g_malloc(), allocating (n_blocks * n_block_bytes ) bytes, but care is taken to detect possible overflow during multiplication.

Since 2.24

g_malloc0_n ()

gpointer
g_malloc0_n (gsize n_blocks,
             gsize n_block_bytes);

This function is similar to g_malloc0(), allocating (n_blocks * n_block_bytes ) bytes, but care is taken to detect possible overflow during multiplication.

Since 2.24

g_realloc_n ()

gpointer
g_realloc_n (gpointer mem,
             gsize n_blocks,
             gsize n_block_bytes);

This function is similar to g_realloc(), allocating (n_blocks * n_block_bytes ) bytes, but care is taken to detect possible overflow during multiplication.

Since 2.24

g_try_malloc_n ()

gpointer
g_try_malloc_n (gsize n_blocks,
                gsize n_block_bytes);

This function is similar to g_try_malloc(), allocating (n_blocks * n_block_bytes ) bytes, but care is taken to detect possible overflow during multiplication.

Since 2.24

g_try_malloc0_n ()

gpointer
g_try_malloc0_n (gsize n_blocks,
                 gsize n_block_bytes);

This function is similar to g_try_malloc0(), allocating (n_blocks * n_block_bytes ) bytes, but care is taken to detect possible overflow during multiplication.

Since 2.24

g_try_realloc_n ()

gpointer
g_try_realloc_n (gpointer mem,
                 gsize n_blocks,
                 gsize n_block_bytes);

This function is similar to g_try_realloc(), allocating (n_blocks * n_block_bytes ) bytes, but care is taken to detect possible overflow during multiplication.

Since 2.24

g_free ()

void
g_free (gpointer mem);

Frees the memory pointed to by mem . If mem is NULL it simply returns.

g_clear_pointer ()

void
g_clear_pointer (gpointer *pp,
                 GDestroyNotify destroy);

Clears a reference to a variable.

pp must not be NULL.

If the reference is NULL then this function does nothing. Otherwise, the variable is destroyed using destroy and the pointer is set to NULL.

This function is threadsafe and modifies the pointer atomically, using memory barriers where needed.

A macro is also included that allows this function to be used without pointer casts.

Since 2.34

g_alloca()

#define             g_alloca(size)

Allocates size bytes on the stack; these bytes will be freed when the current stack frame is cleaned up. This macro essentially just wraps the alloca() function present on most UNIX variants. Thus it provides the same advantages and pitfalls as alloca(): <variablelist> <varlistentry><term></term><listitem><para>

g_newa()

#define             g_newa(struct_type, n_structs)

Wraps g_alloca() in a more typesafe manner.

g_memmove()

#define             g_memmove(dest,src,len)

Copies a block of memory len bytes long, from src to dest . The source and destination areas may overlap.

g_memdup ()

gpointer
g_memdup (gconstpointer mem,
          guint byte_size);

Allocates byte_size bytes of memory, and copies byte_size bytes into it from mem . If mem is NULL it returns NULL.

g_mem_set_vtable ()

void
g_mem_set_vtable (GMemVTable *vtable);

Sets the GMemVTable to use for memory allocation. You can use this to provide custom memory allocation routines.

The vtable only needs to provide malloc(), realloc(), and free() functions; GLib can provide default implementations of the others. The malloc() and realloc() implementations should return NULL on failure, GLib will handle error-checking for you. vtable is copied, so need not persist after this function has been called.

Note that this function must be called before using any other GLib functions.

g_mem_is_system_malloc ()

gboolean
g_mem_is_system_malloc (void);

Checks whether the allocator used by g_malloc() is the system's malloc implementation. If it returns TRUE memory allocated with malloc() can be used interchangeable with memory allocated using g_malloc(). This function is useful for avoiding an extra copy of allocated memory returned by a non-GLib-based API.

A different allocator can be set using g_mem_set_vtable().

g_mem_profile ()

void
g_mem_profile (void);

Outputs a summary of memory usage.

It outputs the frequency of allocations of different sizes, the total number of bytes which have been allocated, the total number of bytes which have been freed, and the difference between the previous two values, i.e. the number of bytes still in use.

Note that this function will not output anything unless you have previously installed the glib_mem_profiler_table with g_mem_set_vtable().

g_mem_gc_friendly

extern gboolean g_mem_gc_friendly;

This variable is TRUE if the G_DEBUG environment variable includes the key gc-friendly.

struct GMemVTable

struct GMemVTable {
  gpointer (*malloc)      (gsize    n_bytes);
  gpointer (*realloc)     (gpointer mem,
			   gsize    n_bytes);
  void     (*free)        (gpointer mem);
  /* optional; set to NULL if not used ! */
  gpointer (*calloc)      (gsize    n_blocks,
			   gsize    n_block_bytes);
  gpointer (*try_malloc)  (gsize    n_bytes);
  gpointer (*try_realloc) (gpointer mem,
			   gsize    n_bytes);
};

A set of functions used to perform memory allocation. The same GMemVTable must be used for all allocations in the same program; a call to g_mem_set_vtable(), if it exists, should be prior to any use of GLib.

glib_mem_profiler_table

extern GMemVTable *glib_mem_profiler_table;

A GMemVTable containing profiling variants of the memory allocation functions. Use them together with g_mem_profile() in order to get information about the memory allocation pattern of your program.