🔴 Advanced · Lesson 39

Stack using C

Stack

A stack is a linear data structure that follows LIFO: Last In, First Out. The last inserted element is removed first.

Operation	Meaning
Push	Insert element at top
Pop	Remove top element
Peek	View top element
isEmpty	Check whether stack is empty
isFull	Check overflow condition

Overflow and Underflow

⚠️ Stack Conditions

Overflow: pushing when stack is full
Underflow: popping when stack is empty

Array Implementation

C Language

#include <stdio.h>
#define SIZE 5

int stack[SIZE], top = -1;

void push(int value) {
    if(top == SIZE - 1) {
        printf("Stack Overflow\n");
        return;
    }
    stack[++top] = value;
}

int pop() {
    if(top == -1) {
        printf("Stack Underflow\n");
        return -1;
    }
    return stack[top--];
}

int peek() {
    if(top == -1) return -1;
    return stack[top];
}

int main() {
    push(10); push(20); push(30);
    printf("Top = %d\n", peek());
    printf("Popped = %d\n", pop());
    printf("Top = %d", peek());
    return 0;
}

Top = 30 Popped = 30 Top = 20

Summary

Stack follows LIFO order
Top variable tracks the last inserted element
Push inserts at top
Pop removes from top
Used in recursion, expression evaluation and undo operations

Stack

Stack एक linear data structure है जो LIFO follow करता है: Last In, First Out.

Operations

Operation	Meaning
Push	Top पर insert
Pop	Top से remove
Peek	Top value देखना
Overflow	Stack full होने पर push
Underflow	Empty stack से pop

Array Implementation

C Language

#define SIZE 5
int stack[SIZE], top = -1;

void push(int value) {
    if(top == SIZE - 1) printf("Overflow");
    else stack[++top] = value;
}

int pop() {
    if(top == -1) return -1;
    return stack[top--];
}

सारांश

Stack LIFO follow करता है
top last inserted element को track करता है
Push insert करता है
Pop remove करता है
Recursion और undo जैसी operations में use होता है

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