Type Alias


A prototype for a function callback that reallocates memory of a requested size for an existing block of memory.




The block of memory to resize.


The size of the new allocation.


A bitfield that is currently not used (always set to 0).


An untyped pointer to program-defined data.

Return Value

Pointer to the new block of memory.


In implementing this function, change the size of the block of memory pointed to by ptr to the size specified by newsize and return the pointer to the larger block of memory. Return NULL on any reallocation failure, leaving the old block of memory untouched. Also return NULL immediately if any of the following conditions if the ptr parameter is NULL or the newsize parameter is not greater than 0. Leave the contents of the old block of memory unchanged up to the lesser of the new or old sizes. If the ptr parameter is not a block of memory that has been previously allocated by the allocator, the results are undefined; abnormal program termination can occur. The hint argument is a bitfield that you should currently not use (that is, assign 0).

See Also


typealias CFAllocatorAllocateCallBack

A prototype for a function callback that allocates memory of a requested size.

typealias CFAllocatorCopyDescriptionCallBack

A prototype for a function callback that provides a description of the specified data.

typealias CFAllocatorDeallocateCallBack

A prototype for a function callback that deallocates a block of memory.

typealias CFAllocatorPreferredSizeCallBack

A prototype for a function callback that gives the size of memory likely to be allocated, given a certain request.

typealias CFAllocatorReleaseCallBack

A prototype for a function callback that releases the given data.

typealias CFAllocatorRetainCallBack

A prototype for a function callback that retains the given data.

Beta Software

This documentation contains preliminary information about an API or technology in development. This information is subject to change, and software implemented according to this documentation should be tested with final operating system software.

Learn more about using Apple's beta software