>>761
typedef struct {int num; char data[100];} Stack;

void init(Stack *stack) {
stack->num = 0;
}

char push(char c, Stack *stack) {
if (stack->num >= sizeof(stack->data)) return 0; /* error */
stack->data[stack->num++] = c;
return 1; /* success */
}

char pop(char c, Stack *stack) {
if (stack->num == 0) return 0; /* error */
return stack->data[--(stack->num)];
}