Array Implementation of STACK (abstract data type) in C programming.

ListStack.c

#include <stdio.h>
#include <stdlib.h>
#include <assert.h>

struct stack {
    int * keys;
    int max_size;
    int peek;
};

// defining a new type stck of struct stack.
typedef struct stack stck;

//Function prototpye or method on stack.
stck * create_stack(int); // create_stack will initiate the stack.
unsigned is_empty(stck); // isEmpty will tells weather a stack is empty.
unsigned is_full(stck); // isFull will tells weather a stack is full.
int get_peek(stck); // Peek will return the top most element of the stack.
void push(int, stck *); // push key into the stack.
void pop(stck *); //Pop will delete the last element of the stack.

stck * create_stack(int max_size) {
    stck * st;
    st = malloc(sizeof(stck));
    st->peek = -1;
    st->max_size = max_size;
    st->keys = malloc(max_size * sizeof(int));
    return st;
}

unsigned is_empty(stck st) {
    return st.peek == -1;
}

unsigned is_full(stck st) {
    return st.peek == st.max_size -1;
}

int get_peek(stck st) {
    assert(!is_empty(st));
    return st.keys[st.peek];
}

void push(int key, stck * st) {
    // stack overflow
    assert(!is_full(*st));
    st->keys[++st->peek] = key;
}

void pop(stck * st) {
    // stack underflow
    assert(!is_empty(*st));
    st->peek--;
}

int main() {
    int stack_max_size = 100, index;
    stck * st = create_stack(stack_max_size);
    for (index = 0; index < 10; index++) {
        push(index, &st);
    }

    while (!is_empty(*st)) {
        printf("%d -- ", get_peek(*st));
        pop(&st);
    }
    return 0;
}