infix to postfix.cpp

#include <iostream>
#include <stack>
#include <string>

using namespace std;

// Function to get the precedence of an operator
int precedence(char op) {
    if (op == '+' || op == '-') {
        return 1;
    }
    else if (op == '*' || op == '/') {
        return 2;
    }
    else if (op == '^') {
        return 3;
    }
    return 0;
}

// Function to convert infix expression to postfix expression
string infixToPostfix(string infix) {
    stack<char> s;
    string postfix = "";
    for (int i = 0; i < infix.length(); i++) {
        char c = infix[i];
        if (isalnum(c)) {
            postfix += c;
        }
        else if (c == '(') {
            s.push(c);
        }
        else if (c == ')') {
            while (!s.empty() && s.top() != '(') {
                postfix += s.top();
                s.pop();
            }
            if (!s.empty() && s.top() == '(') {
                s.pop();
            }
        }
        else {
            while (!s.empty() && precedence(c) <= precedence(s.top())) {
                postfix += s.top();
                s.pop();
            }
            s.push(c);
        }
    }
    while (!s.empty()) {
        postfix += s.top();
        s.pop();
    }
    return postfix;
}

int main() {
    string infix = "a+b*c-d/e";
    string postfix = infixToPostfix(infix);
    cout << "Infix expression: " << infix << endl;
    cout << "Postfix expression: " << postfix << endl;
    return 0;
}