Data Structures and Algorithms — Complete Course Notes (BCA 3rd Sem)

A stack is a Last-In, First-Out (LIFO) abstract data structure where insertions and deletions happen only at one end called the top.

Primary Operations:

• push(item): Add an element to the top. Checks for Stack Overflow.
• pop(): Remove the element from the top. Checks for Stack Underflow.
• peek(): Inspect the current top element without removing it.

```c #define MAX 100 int stack[MAX]; int top = -1;

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

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