malloc(3x)																malloc(3x)

Name
       malloc, free, realloc, calloc, mallopt, mallinfo - fast main memory allocator

Syntax
       #include <malloc.h>

       char *malloc (size)
       unsigned size;

       void free (ptr)
       char *ptr;

       char *realloc (ptr, size)
       char *ptr;
       unsigned size;

       char *calloc (nelem, elsize)
       unsigned nelem, elsize;

       int mallopt (cmd, value)
       int cmd, value;

       struct mallinfo mallinfo (max)
       int max;

Description
       The  and  subroutines  provide  a simple general-purpose memory allocation package, which runs considerably faster than the package.  It is
       found in the library and is loaded if the option is used with or

       The subroutine returns a pointer to a block of at least size bytes suitably aligned for any use.

       The argument to is a pointer to a block previously allocated by After is performed, this space is made available  for  further  allocation,
       and its contents have been destroyed.  See below for a way to change this behavior.

       Undefined results will occur if the space assigned by is overrun or if some random number is handed to

       The subroutine changes the size of the block pointed to by ptr to size bytes and returns a pointer to the (possibly moved) block.  The con-
       tents will be unchanged up to the lesser of the new and old sizes.

       The subroutine allocates space for an array of nelem elements of size elsize.  The space is initialized to zeros.

       The subroutine provides for control over the allocation algorithm.  The available values for cmd are:

       M_MXFAST Set maxfast to value .	The algorithm allocates all blocks below the size of maxfast in large groups and then doles them out  very
		quickly.  The default value for maxfast is 0.

       M_NLBLKS Set numlblks to value .  The above mentioned large groups each contain numlblks blocks.  The numlblks must be greater than 0.  The
		default value for numlblks is 100.

       M_GRAIN	Set grain to value .  The sizes of all blocks smaller than maxfast are considered to be rounded up  to	the  nearest  multiple	of
		grain  .  The grain must be greater than 0.  The default value of grain is the smallest number of bytes which will allow alignment
		of any data type.  Value will be rounded up to a multiple of the default when grain is set.

       M_KEEP	Preserve data in a freed block until the next or This option is provided only for compatibility with the old version of and is not
		recommended.

       These values are defined in the malloc.h header file.

       The subroutine may be called repeatedly, but may not be called after the first small block is allocated.

       The subroutine provides information describing space usage.  It returns the following structure:
       struct mallinfo	{
	       int arena;      /* total space in arena */
	       int ordblks;    /* number of ordinary blocks */
	       int smblks;     /* number of small blocks */
	       int hblkhd;     /* space in holding block headers */
	       int hblks;      /* number of holding blocks */
	       int usmblks;    /* space in small blocks in use */
	       int fsmblks;    /* space in free small blocks */
	       int uordblks;   /* space in ordinary blocks in use */
	       int fordblks;   /* space in free ordinary blocks */
	       int keepcost;   /* space penalty if keep option */
			       /* is used */
       }

       This structure is defined in the malloc.h header file.

       Each  of  the  allocation routines returns a pointer to space suitably aligned (after possible pointer coercion) for storage of any type of
       object.

Restrictions
       This package usually uses more data space than
       The code size is also bigger than
       Note that unlike this package does not preserve the contents of a block when it is freed, unless the M_KEEP option of is used.
       Undocumented features of have not been duplicated.

Return Values
       The and subroutines return a NULL pointer if there is not enough available memory.  When returns NULL, the block pointed to by ptr is  left
       intact.	If is called after any allocation or if cmd or value are invalid, nonzero is returned.	Otherwise, it returns zero.

See Also
       brk(2), malloc(3)

																	malloc(3x)