C program to implement Stack using array

Stack implementation using array in C: In this tutorial, we will learn to implement a stack using an array and using stack structure with the help of C programs. By IncludeHelp Last updated : July 30, 2023

A STACK is a simple Data Structure, it can be implemented as an array or as Linked List, Stack has only One TOP End, item can be pushed (add) and popped (remove) by only this End (TOP Pointer). Array follows LIFO (Last In First Out) property, it means the Item that is inserted Last will be popped first.

Stack implementation using an array in C

In this C program, we are implementing a stack using an array with various stack operations such as display, insert, remove, and pop.

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

#define MAX 10

int STACK[MAX], TOP;
/* display stack element*/
void display(int[]);

/* push (insert) item into stack*/
void PUSH(int[], int);

/* pop (remove) item from stack*/
void POP(int[]);

void main()
{
    int ITEM = 0;
    int choice = 0;
    TOP = -1;

    while (1) {
        /*clrscr();*/
        printf("Enter Choice (1: display, 2: insert (PUSH), 3: remove(POP)), 4: Exit..: ");
        scanf("%d", &choice);

        switch (choice) {
        case 1:
            display(STACK);
            break;
        case 2:
            printf("Enter Item to be insert :");
            scanf("%d", &ITEM);
            PUSH(STACK, ITEM);
            break;
        case 3:
            POP(STACK);
            break;
        case 4:
            exit(0);
        default:
            printf("\nInvalid choice.");
            break;
        }
    } // end of while(1)
}

/*  function    : display(),
to display stack elements.
*/
void display(int stack[])
{
    int i = 0;
    if (TOP == -1) {
        printf("Stack is Empty .\n");
        return;
    }

    printf("%d <-- TOP ", stack[TOP]);
    for (i = TOP - 1; i >= 0; i--) {
        printf("\n%d", stack[i]);
    }
    printf("\n\n");
}

/*  function    : PUSH(),
to push an item into stack.
*/
void PUSH(int stack[], int item)
{
    if (TOP == MAX - 1) {
        printf("\nSTACK is FULL CAN't ADD ITEM\n");
        return;
    }
    TOP++;
    stack[TOP] = item;
}

/*  function    : POP(),
to pop an item from stack.
*/
void POP(int stack[])
{
    int deletedItem;
    if (TOP == -1) {
        printf("STACK is EMPTY.\n");
        return;
    }

    deletedItem = stack[TOP];
    TOP--;
    printf("%d deleted successfully\n", deletedItem);
    return;
}

Output:

Enter Choice (1: display, 2: insert (PUSH), 3: remove(POP)), 4: Exit..: 2
Enter Item to be insert :10
Enter Choice (1: display, 2: insert (PUSH), 3: remove(POP)), 4: Exit..: 2
Enter Item to be insert :20
Enter Choice (1: display, 2: insert (PUSH), 3: remove(POP)), 4: Exit..: 1
20 <-- TOP 
10

Enter Choice (1: display, 2: insert (PUSH), 3: remove(POP)), 4: Exit..: 2
Enter Item to be insert :30
Enter Choice (1: display, 2: insert (PUSH), 3: remove(POP)), 4: Exit..: 2
Enter Item to be insert :40
Enter Choice (1: display, 2: insert (PUSH), 3: remove(POP)), 4: Exit..: 1
40 <-- TOP 
30
20
10

Enter Choice (1: display, 2: insert (PUSH), 3: remove(POP)), 4: Exit..: 3
40 deleted successfully
Enter Choice (1: display, 2: insert (PUSH), 3: remove(POP)), 4: Exit..: 3
30 deleted successfully
Enter Choice (1: display, 2: insert (PUSH), 3: remove(POP)), 4: Exit..: 1
20 <-- TOP 
10

Enter Choice (1: display, 2: insert (PUSH), 3: remove(POP)), 4: Exit..: 4

Stack implementation using array structure in C

In this C program, we are implementing a stack using a structure with an array i.e., an array structure with various stack operations such as display, insert, remove, and pop.

#include <stdio.h>

#define MAX 100

/* declaration*/
typedef struct
    {
    int ele[MAX];
    int TOP;
} STACK;

STACK* s;

/* function: pushItem( ), to insert an item into stack. */
void pushItem(STACK* s, int ITEM)
{
    if (s->TOP == MAX - 1)

    {
        printf("\nSTACK is FULL.\n");
        return;
    }
    s->ele[++s->TOP] = ITEM;
    printf("\nITEM inserted successfully.\n");
}

/* function: popItem( ), to delete an item from stack. */
int popItem(STACK* s)
{

    int itm;
    if (s->TOP == -1) {
        printf("\nSTACK is empty.\n");
        return;
    }
    itm = s->ele[s->TOP];
    s->TOP--;
    printf("\nItem removed : %d\n", itm);
}

/* function: dispItem( ), to display stack elements. */
void dispItems(STACK* s)
{
    int i;
    if (s->TOP == -1) {
        printf("STACK IS EMPTY.");
        return;
    }
    for (i = s->TOP; i >= 0; i--)
        printf("%d->", s->ele[i]);

    printf("\n");
}

/*** main function **/
void main()
{
    int num;
    char dummy;

    /** initialisation**/

    s = (STACK*)malloc(sizeof(STACK));
    s->TOP = -1;

    int choice = 0;

again:

    /* display stack elements **/
    printf("\nSTACK ELEMENTS :");
    dispItems(s);

    printf("\nSTACK OPTIONS \n0: Exit\n1: Add item\n2: Remove item \nEnter choice :::");
    scanf("%d", &choice);

    switch (choice) {

    case 0:
        exit(1);
        break;

    case 1:
        printf("\nEnter an item to insert:");
        scanf("%d", &num);
        pushItem(s, num);
        break;

    case 2:
        popItem(s);
        break;

    default:
        printf("\nAn Invalid Choice !!!");
        break;
    }

    scanf("%c", &dummy);
    goto again;
}

Output:

    STACK ELEMENTS :44->33->22->11->
    STACK OPTIONS 
    0: Exit
    1: Add item
    2: Remove item 
    Enter choice :::1

    Enter an item to insert:55