C++ - Stacks Part 3: Practical Applications of Stacks

Stacks are used in algorithms that require LIFO operations, such as parsing, recursion simulation, and backtracking.

Examples and Explanation

Reversing a String

std::stack<char> charStack;

std::string str = "hello";

for (char c : str) {

    charStack.push(c);

}

while (!charStack.empty()) {

    std::cout << charStack.top();

    charStack.pop();

}

// Output: olleh

Explanation: Characters are pushed into the stack in order and then popped out in reverse order.

Checking Balanced Parentheses

bool isBalanced(const std::string &expression) {

    std::stack<char> stack;

    for (char c : expression) {

        if (c == '(') stack.push(c);

        else if (c == ')') {

            if (stack.empty()) return false;

            stack.pop();

        }

    }

    return stack.empty();

}

Explanation: Stacks help in keeping track of unmatched parentheses, a common task in parsing expressions.

Implementing Undo Functionality

std::stack<std::string> undoStack;

undoStack.push("Action1");

undoStack.push("Action2");

std::cout << "Undo: " << undoStack.top(); // Output: Action2

undoStack.pop();

Explanation: Stacks provide an easy way to implement undo/redo functionality by managing the sequence of actions.