August 11, 2002 ALLOCA 3

### NAME

alloca - memory allocator

### LIBRARY

Standard C Library (libc, -lc)

### SYNOPSIS

```void``*` alloca(```size_t size`)

### DESCRIPTION

The alloca(``) function allocates ```size` bytes of space in the stack frame of the caller. This temporary space is automatically freed on return.

### RETURN VALUES

The alloca(``) function returns a pointer to the beginning of the allocated space. If the allocation failed, a ```NULL` pointer is returned.

### SEE ALSO

brk(2), calloc(3), getpagesize(3), malloc(3), realloc(3)

### BUGS

The alloca(``) function is machine dependent; its use is discouraged.

The alloca(``) function is slightly unsafe because it cannot ensure that the pointer returned points to a valid and usable block of memory. The allocation made may exceed the bounds of the stack, or even go further into other objects in memory, and alloca(``) cannot determine such an error. Avoid alloca(``) with large unbounded allocations.