postfix_calculation_using_stack.cpp

#include <iostream>
#include <string.h>
#include <sstream>
using namespace std;

template <class T>
class AStack {
private:
    T * arr;
    int size;
    int maxSize;
public:
    AStack(int size) {
        this->maxSize = size;
        this->size = 0;
        arr = new T[size];
    }

    ~AStack() {
        delete[] arr;
    }

    void push(const T & element) {
        if (size < maxSize) {
            arr[size] = element;
            this->size += 1;
        }
        else {
            throw("Stack is full\n");
        }
    }

    T & pop() {
        if (this->size == 0) {
            throw("Stack is empty");
        }
        else {
            static T returnData;
            returnData = arr[size - 1];
            this->size -= 1;
            return returnData;
        }
    }

    bool isFull() {
        return this->size == maxSize;
    }

    bool isEmpty() {
        return this->size == 0;
    }

    void printStack() {
        cout << "================\nStack:\n";
        int i = 0;
        for (i = this->size - 1; i >= 0; i--) {
            cout << arr[i] << endl;
        }
    }

    void clear() {
        delete[] arr;
        arr = new T[maxSize];
    }
};

int add(int a, int b) {
    return a + b;
}

int sub(int a, int b) {
    return a - b;
}

int multiply(int a, int b) {
    return a * b;
}

int divide(int a, int b) {
    return b / a;
}

int main(int argc, char const * argv[])
{
    AStack<int> * stack = new AStack<int>(10);
    string command = "7 4 -3 * 1 5 + / *";
    stringstream ss(command);
    string str;

    int (*operation)(int, int);

    while (getline(ss, str, ' ')) {
        if (str == "+" || str == "-" || str == "*" || str == "/") {
            if (str == "+") {
                operation = &add;
            }
            else if (str == "-") {
                operation = &sub;
            }
            else if (str == "*") {
                operation = &multiply;
            }
            else {
                operation = &divide;
            }
            int num_1 = stack->pop();
            int num_2 = stack->pop();
            int res = (*operation)(num_1, num_2);
            stack->push(res);
        }
        else {
            stack->push(stoi(str));
        }
    }
    cout << "Result: " << (stack->pop()) << endl;
    return 0;
}