infix,postfix

#include<cstdio>
#include <ctype.h>
#include <map>
#include <string>
#include <iostream>
#include <stack>
#include <fstream>



using namespace std;



map<char, int> charPriorty;
stack<char> s;
FILE *writeFile, *readFile;




void postfix(string infix, int f) {


    charPriorty['+'] = 1;
    charPriorty['-'] = 1;
    charPriorty['*'] = 2;
    charPriorty['/'] = 2;





    char  postfixString[100];
    int j=0;

    int i = 0;


    while (infix[i] != '\0') {

        if ((infix[i] >= 'a' && infix[i] <= 'z') || (infix[i] >= '0' && infix[i] <= '9')) {

           // cout << infix[i] << " ";
            postfixString[j] = infix[i];
            j++;
        } else if (infix[i] == '(') {

            s.push(infix[i]);
        } else if (infix[i] == ')') {

            while (s.top() != '(') {

                //cout << s.top() << " ";
                postfixString[j] = s.top();
                j++;
                s.pop();
            }
            s.pop();

        } else if (s.size() == 0) {
            s.push(infix[i]);
        } else if ((infix[i] == '+' || infix[i] == '-') and (s.top() == '*' || s.top() == '/')) {
            while (s.size() != 0) {

                if (s.top()  == '(')
                    break;
               // cout << s.top() << " ";
                postfixString[j] = s.top();
                j++;
                s.pop();
            }

            s.push(infix[i]);

        } else if ( charPriorty[infix[i]] == charPriorty[s.top()]) {

           // cout << s.top() << " ";
            postfixString[j] = s.top();
            j++;
            s.pop();
            s.push(infix[i]);

        } else{

            s.push(infix[i]);
        }

        i++;
    }

    while(!s.empty()){

       // cout<<s.top()<<" ";
        postfixString[j] = s.top();
        j++;
        s.pop();

    }

    postfixString[j] = '\0';

    //cout<<"\n"<<postfixString<<endl;



    if(f == 2){


        cout<<"Please Check file.txt For Postfix  Expression....\n";

        writeFile = fopen("file.txt", "a");
        fprintf(writeFile, "%s", postfixString);

        fclose(writeFile);


    } else

        cout<<"Postfix : "<<postfixString<<endl;


}



void prefix(string prefix, int f){



    charPriorty['+'] = 1;
    charPriorty['-'] = 1;
    charPriorty['*'] = 2;
    charPriorty['/'] = 2;


    int len = prefix.size();

    int i=0;
    int j = len-1;
    while(i<j){

        char temp = prefix[i];
        prefix[i] = prefix[j];
        prefix[j] = temp;
        i++;
        j--;

    }

    //cout<<"Prefix : "<<prefix<<endl;




     i = 0;

    j=0;

    char  prefixString[100];

    while (prefix[i] != '\0') {



        if ((prefix[i] >= 'a' && prefix[i] <= 'z') || (prefix[i] >= '0' && prefix[i] <= '9')){

            //cout << prefix[i] << " ";
            prefixString[j] =prefix[i];
            j++;
        } else if (prefix[i] == ')') {

            s.push(prefix[i]);
        } else if (prefix[i] == '(') {

            while (s.top() != ')') {

                //cout << s.top() << " ";
                prefixString[j] = s.top();
                j++;
                s.pop();
            }
            s.pop();

        } else if (s.size() == 0) {
            s.push(prefix[i]);
        } else if ((prefix[i] == '+' || prefix[i] == '-') and (s.top() == '*' || s.top() == '/')) {
            while ( s.size() != 0 ) {

                if(s.top() ==')')
                    break;

                prefixString[j] = s.top();
                j++;
                s.pop();

            }

            s.push(prefix[i]);

        } else if ( charPriorty[prefix[i]] ==charPriorty[s.top()]) {

            //cout << s.top() << " ";

            //prefixString[j] = s.top();
            //j++;
            //s.pop();

            s.push(prefix[i]);

        } else{

            s.push(prefix[i]);
        }

        i++;
    }

    while(!s.empty()){

       // cout<<s.top()<<" ";
        prefixString[j] = s.top();
        j++;

        s.pop();

    }

    prefixString[j] = '\0';

     i=0;

     j = j-1;

    while(i<j){

        char temp = prefixString[i];
        prefixString[i] = prefixString[j];
        prefixString[j] = temp;
        i++;
        j--;

    }


    if(f == 2){


        cout<<"Please Check file.txt For Infix  Expression....\n";
        writeFile = fopen("file.txt", "a");
        fprintf(writeFile, "%s", prefixString);

        fclose(writeFile);


    } else

        cout<<"Infix : "<<prefixString<<endl;




}




int main()
{







    bool decision = true;

    while(decision){

        cout<<endl<<"1. Console Input :\n";
        cout<<"2. File Input :\n";
        cout<<"3. Exit() :\n\n";


        int n;
        cin>>n;

        if(n == 1 ){


            cout<<"\nPlease Enter Infix Expression :  ";
            string infixInput;

            cin>>infixInput;

            cout<<"1 For Prefix Conversion"<<endl;
            cout<<"2 For Postfix Conversion"<<endl;



            int x;
            cin>>x;



            if(x==1){

                prefix(infixInput,1);
            }
            if (x==2){

                postfix(infixInput, 1);
            }


        } else if(n == 2 ){


            cout<<"\nInfix Expression has read from file............\n\n";

            char name[100];

            readFile = fopen("file.txt", "r");
            fscanf(readFile, "%s", name);

            fclose(readFile);




            cout<<"1 For Prefix Conversion"<<endl;
            cout<<"2 For Postfix Conversion"<<endl;



            int x;
            cin>>x;



            if(x==1){

                prefix(name ,2 );
            }
            if (x==2){

                postfix(name, 2);
            }


        }



        else if(n == 3){

            decision = false;

        }




}

    return  0;

}