postfixEvaluation.cpp

#include <iostream>
#include <string>
#include <stack>
#include <math.h>
using namespace std;
int postfixEvaluation(string str)
{
    stack<int> st;
    for (int i = 0; i < str.length(); i++)
    {
        if (str[i] >= '0' && str[i] <= '9')
        {
            st.push(str[i]-'0');
        }
        else{
            int op2 = st.top();
            st.pop();
            int op1 = st.top();
            st.pop();

            switch (str[i])
            {
            case '+':
                st.push(op1+op2);
                break;
            case '-':
                st.push(op1-op2);
                break;
            case '*':
                st.push(op1*op2);
                break;
            case '/':
                st.push(op1/op2);
                break;
            case '^':
                st.push(pow(op1,op2));
            }
        }
    }
    return st.top();
}
int main()
{
    string equation = "46+2/5*7+";
    cout<<postfixEvaluation(equation)<<endl;
    return 0;
}