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Data Structures in C/C++

Stack Data Structure

Implement last-in, first-out operations.

What is Stack Data Structure?

A stack exposes only its top: push adds, pop removes, and peek reads the newest item.

Important points

  • State the invariants before implementing operations.
  • Handle empty, full, and allocation-failure cases.
  • Measure time complexity and memory ownership together.

See how it works

Push and pop to see that the last item in is always the first one out.

C and C++ code examples

C
Run code →
main.c
#include <stdio.h>

typedef struct {
    int data[8];
    int size;
} Stack;

int push(Stack *stack, int value) {
    if (stack->size == 8) return 0;
    stack->data[stack->size++] = value;
    return 1;
}

int pop(Stack *stack, int *value) {
    if (stack->size == 0) return 0;
    *value = stack->data[--stack->size];
    return 1;
}

int main(void) {
    Stack stack = {{0}, 0};
    int value;
    push(&stack, 10);
    push(&stack, 20);
    pop(&stack, &value);
    printf("%d\n", value);
}
Result of running the code
20
C++
Run code →
main.cpp
#include <iostream>
#include <stack>

int main() {
    std::stack<int> values;
    values.push(10);
    values.push(20);
    std::cout << values.top() << '\n';
    values.pop();
}
Result of running the code
20

C and C++ comparison

The fixed-capacity C implementation must detect overflow and underflow. std::stack manages capacity through its underlying container and offers the same LIFO interface.

C

Structures and operations are usually separate and allocation is explicit.

C++

Classes and containers can preserve invariants and manage resources automatically.

Practice exercises

Run both versions, then modify them to observe the different language guarantees.

  • Add empty and capacity-boundary tests.
  • Implement cleanup and verify no leaks remain.
  • Compare operation complexity with a standard container.

Practice with a challenge

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