Infix_To_Postfix.cpp

#include <iostream>
#include <stack>
#include <cctype>
using namespace std;

int precedence(char op) {
    if (op == '^') return 3;
    if (op == '*' || op == '/') return 2;
    if (op == '+' || op == '-') return 1;
    return 0;
}

string toPostfix(const string& infix) {
    stack<char> ops;
    string postfix;

    for (size_t i = 0; i < infix.length(); ++i) {
        char c = infix[i];

        if (isdigit(c)) {
            // Extract full number
            while (i < infix.length() && isdigit(infix[i])) {
                postfix += infix[i++];
            }
            postfix += ' ';
            i--; // adjust loop index
        }
        else if (c == '(') {
            ops.push(c);
        }
        else if (c == ')') {
            while (!ops.empty() && ops.top() != '(') {
                postfix += ops.top(); postfix += ' ';
                ops.pop();
            }
            if (!ops.empty()) ops.pop(); // remove '('
        }
        else {
            while (!ops.empty() && precedence(ops.top()) >= precedence(c)) {
                postfix += ops.top(); postfix += ' ';
                ops.pop();
            }
            ops.push(c);
        }
    }

    // Flush remaining operators
    while (!ops.empty()) {
        postfix += ops.top(); postfix += ' ';
        ops.pop();
    }

    return postfix;
}

int main() {
    string infix;
    cout << "Enter infix expression: ";
    cin >> infix;

    string postfix = toPostfix(infix);
    cout << "Postfix Expression: " << postfix << endl;

    return 0;
}
//12*5+(20/5)