Compiler

#include <bits/stdc++.h>
#include <fstream>
#include<stdio.h>
#include<string>
using namespace std;

string result1;
string result2;
string prefixConverter(string st);
string postfixConverter(string st);
void consoleInput();
void fileInput();
int setPrecedence(char ch);

int main()
{
        printf("    Name : MD. Abir Ahsan \n");
        printf("      ID : 011 172 077 \n");

        printf("\n$$~~~ Menu ~~~$$ ");

            int choice;

    for( ; ; )
    {
        printf("\n1. Console Input \n");
        printf("2. File Input \n");
        printf("3.Exit\n");

        printf("enter your choice :");
        cin >> choice;

    if (choice == 1)
        consoleInput();

    else if (choice == 2)
        fileInput();

    else if (choice == 3)
        exit(0);


    }
    return 0;
}

void consoleInput()
{
    string st;
    int choice2;

    printf(" Enter infix expression: ");
    cin >> st;

    printf("\n1. Convert to Prefix \n");
    printf("2. Convert to Postfix \n");

    printf("Enter your choice :");
    cin >> choice2;

    if (choice2 == 1)
    {
        cout << "Prefix expression : " << prefixConverter(st) << endl;
        result2.clear();
        result1.clear();
    }
    else if (choice2 == 2)
    {
        cout << "Postfix expression : " << postfixConverter(st) << endl;
        result2.clear();
        result1.clear();
    }
}

void fileInput()
{
    ifstream f_in;

    int choice3;
    string loc, line;
    printf("\nEnter File location: ");
    cin >> loc;

    f_in.open(loc.c_str());

    if (f_in.is_open())
    {
        while (getline(f_in,line))
        {
            printf("\n1. Convert to Prefix \n");
            printf("2. Convert to Postfix \n");

            printf("\nEnter your choice:");
            cin >> choice3;

            if (choice3 == 1)
            {
                prefixConverter(line);
            }
            else if (choice3 == 2)
            {
                postfixConverter(line);
            }

        }
    }
    else
    {
        std::cout << "Unable to open file" << std::endl << std::endl;
    }

    f_in.close();

    ofstream f_out;
    f_out.open(loc.c_str());

    if (choice3==1)
    {
        f_out << result1 << endl;
        cout << "Output written in File." << endl;
        result1.clear();
        result2.clear();
    }

    else if (choice3==2)
    {
        f_out << result2 << endl;
        cout << "Output written in File." << endl;
        result1.clear();
        result2.clear();
    }
    f_out.close();
}

string prefixConverter(string st)
{
    reverse(st.begin(), st.end());

    for (int i=0;i<st.size();i++)
    {
        if (st[i] == '(')
        {
            st[i] = ')';
            i++;
        }
        else if (st[i] == ')')
        {
            st[i] = '(';
            i++;
        }
    }
    result1 = postfixConverter(st);
    reverse(result1.begin(), result1.end());

    return result1;
}

string postfixConverter(string st)
{
    st = '(' + st + ')';

    stack<char> stk1;

    for (int i= 0; i < st.size(); i++)
    {
        if (isalpha(st[i]) || isdigit(st[i]))
        {
            result2 += st[i];
        }
        else if (st[i] == '(')
        {
            stk1.push('(');
        }
        else if (st[i] == ')')
        {
            while (stk1.top() != '(')
            {
                result2 += stk1.top();
                stk1.pop();
            }
            stk1.pop();
        }
        else
        {
            if (!isalpha(stk1.top()) && !isdigit(stk1.top()))
            {
                while ( setPrecedence(st[i]) <= setPrecedence((stk1.top())) )
                {
                    result2+= stk1.top();
                    stk1.pop();
                }
                stk1.push(st[i]);
            }
        }
    }

    return result2;
}

int setPrecedence(char ch)
{
    if (ch == '+' || ch == '-')
        return 1;
    else if (ch == '*' || ch == '/')
        return 2;
    else if (ch == '^')
        return 3;
    else
        return -1;
}