realloc

Reallocates a block of memory

Local Servers:blocking
Remote Servers:N/A
Classification:ANSI
Service:Memory Allocation

Syntax

  #include <nwmalloc.h> 
  #include <stdlib.h>  
   
  void *realloc  (  
     void     *oldBlk,   
     size_t    size);

Parameters

oldBlk
(IN) Points to a previously allocated memory block.
size
(IN) Specifies the size (in bytes) of the memory block.

Return Values

realloc returns a pointer to the start of the reallocated memory. The return value is NULL if there is insufficient memory available or if the requested size is 0.

Remarks

The realloc function calls the malloc function to enlarge a block of memory.

Memory allocation is not limited to 64 KB. The size parameter is 32 bits.

When the value of the oldBlk parameter is NULL, a new block of memory of size bytes is allocated. Otherwise, the realloc function reallocates space of an object of size bytes by either:

  • Shrinking the allocated size of the allocated memory block oldBlk when size is sufficiently smaller than the size of oldBlk.
  • Allocating a new block and copying the contents of oldBlk to the new block when size is not sufficiently smaller than the size of oldBlk.

Because it is possible that a new block can be allocated, no other pointers should point into the memory of oldBlk. When a new block is allocated, these pointers point to freed memory, with possibly disastrous results.

See Also

calloc, free, malloc

Example

  #include <nwmalloc.h>  
  #include <stdlib.h> 
   
  main ()  
  {  
     char      *memoryPointer;  
     char      *oldBlk;  
     size_t     size;  
     memoryPointer = realloc (oldBlk, size);  
  }