arraystack-full.c

#include <stdio.h>
#define MAX 5

int stack_arr[MAX];
int top = -1;

// 1. Helper function to check if full
int isFull() {
    if (top == MAX - 1) return 1;
    return 0;
}

// 2. Helper function to check if empty
int isEmpty() {
    if (top == -1) return 1;
    return 0;
}

// 3. PUSH: Uses isFull()
void push(int data) {
    if (isFull()) { 
        printf("Stack Overflow!\n"); 
        return; 
    }
    stack_arr[++top] = data;  // Pre-increment top and assign
}

// 4. POP: Uses isEmpty()
void pop() {
    if (isEmpty()) { 
        printf("Stack Underflow!\n"); 
        return; 
    }
    printf("Popped: %d\n", stack_arr[top--]); // Print and post-decrement top
}

// 5. PEEK: Uses isEmpty()
void peek() {
    if (isEmpty()) {
        printf("Stack is empty.\n");
        return;
    }
    printf("Top element: %d\n", stack_arr[top]);
}

// 6. DISPLAY: Uses isEmpty()
void display() {
    if (isEmpty()) {
        printf("Stack is empty.\n");
        return;
    }
    printf("Stack elements: ");
    for (int i = top; i >= 0; i--) {
        printf("%d ", stack_arr[i]);
    }
    printf("\n");
}

int main() {
    push(10); 
    push(20);
    
    display();  // Prints: 20 10
    
    pop();      // Pops 20
    peek();     // Top is 10
    
    return 0;
}