C Programming :: Dynamic Memory Allocation - Discussion

The alloca() function allocates size bytes of space in the stack frame of the caller.  This temporary space is automatically freed when the function that called alloca() returns to its caller. The alloca() function returns a pointer to the beginning of the allocated space.  If the allocation causes stack overflow, program behavior is undefined.

If you are using alloca function, then you need to include below library in your program.

       #include <alloca.h>

Prototype of alloca:
       void *alloca(size_t size);