Queue with two stacks

Implement a queue using two stacks. The operations need not be neccesarily O(1).

/* Include Stack Implementation (using Array)*/
#include "stackimplarray.h"

void queuepush(STACK* st1, STACK* st2, int val)
{
        /* If first stack is empty, push the value straight down */
        if (st1->size == 0)
        {
                st1->items[st1->size++] = val;
                return;
        }

        /* Pop all elements of first stack
           and push it into second stack */
        while(st1->size != 0)
        {
                push(st2, pop(st1));
        }

        /* Push value onto second stack */
        push(st2, val);

    /* Pop all elements of second stack
           and push it into first stack */
        while(st2->size != 0)
        {
                push(st1, pop(st2));
        }
}


/* Driver code to test above functions*/
int main()
{
        STACK stack1, stack2;
        int i;
        for(i=1; i<=10; i++)
        {
                queuepush(&stack1, &stack2, i * 100);
        }

        while(stack1.size != 0)
        {
                printf("%d\n", pop(&stack1));
        }
}