ERROR! invalid operands of types 'float' and 'const char [2]' to binary 'operator<<'

Question

I'm trying to make a program that is an equivalent of a four function calculator for two fractions.. The Error comes up in each of the switch cases within the cout statements. The Error is:

[Error] invalid operands of types 'float' and 'const char [2]' to binary 'operator<<'

I tried googling, nothing found but I did find the same error but with int instead of float. Unfortunately, he was making a clear mistake, he wasn't even using cout statement and putting << operator in the end. Also, I tried adding more parentheses to specify which athematic operations to perform first but it had no effect.

#include <iostream>
#include <conio.h>

using namespace std;

main()
{   //This Program is an equivalent of a four function calculator for fraction
    float N1, D1, N2, D2;
    char OP, slash;
    system("cls");
    
    cout<<"Hint: Enter Both Fractions with Operator in between; 1/2 + 6/3";
    cout<<"\nEnter Fractionaly Binary Operation: ";
    cin>>N1>>slash>>D1>>OP>>N2>>slash>>D2;

    if(slash=='/')
    {
        switch(OP) 
        {
            case '+':
                cout<<"Addition of Given Fraction is: ("<<N1<<"/"<<D1<<") + ("<<N2<<"/"<<D2<<") = "<<(((N1*D2)+(N2*D1))<<"/"<<(D1*D2))<<" = "<<(((N1*D2)+(N2*D1))/(D1*D2))<<endl;
                break;

            case '-':
                cout<<"Subtraction of Given Fraction is: ("<<N1<<"/"<<D1<<") - ("<<N2<<"/"<<D2<<") = "<<(((N1*D2)-(N2*D1))<<"/"<<(D1*D2))<<" = "<<(((N1*D2)-(N2*D1))/(D1*D2))<<endl;
                break;

            case '*':
                cout<<"Multiplication of Given Fraction is: ("<<N1<<"/"<<D1<<") * ("<<N2<<"/"<<D2<<") = "<<((N1*N2)<<"/"<<(D1*D2))<<" = "<<((N1*N2)/(D1*D2))<<endl;
                break;

            case '/':
                cout<<"Division of Given Fraction is: ("<<N1<<"/"<<D1<<") / ("<<N2<<"/"<<D2<<") = "<<((N1*D2)<<"/"<<(D1*N2))<<" = "<<((N1*D2)/(D1*N2))<<endl;
                break;

            default:
                cout<<"INVALID OPERATOR!";
                getch();
                system("cls");
                return(0);
        }
    }
    else
    {
        cout<<"INVALID INPUT!";
        getch();
        system("cls");
        return(0);
    }
    
    
    getch();
    system("cls");
    return(0);
}

The same error is in the following lines..

                case '+':
                    cout<<"Addition of Given Fraction is: ("<<N1<<"/"<<D1<<") + ("<<N2<<"/"<<D2<<") = "<<(((N1*D2)+(N2*D1))<<"/"<<(D1*D2))<<" = "<<(((N1*D2)+(N2*D1))/(D1*D2))<<endl;
                    break;
    
                case '-':
                    cout<<"Subtraction of Given Fraction is: ("<<N1<<"/"<<D1<<") - ("<<N2<<"/"<<D2<<") = "<<(((N1*D2)-(N2*D1))<<"/"<<(D1*D2))<<" = "<<(((N1*D2)-(N2*D1))/(D1*D2))<<endl;
                    break;
    
                case '*':
                    cout<<"Multiplication of Given Fraction is: ("<<N1<<"/"<<D1<<") * ("<<N2<<"/"<<D2<<") = "<<((N1*N2)<<"/"<<(D1*D2))<<" = "<<((N1*N2)/(D1*D2))<<endl;
                    break;
    
                case '/':
                    cout<<"Division of Given Fraction is: ("<<N1<<"/"<<D1<<") / ("<<N2<<"/"<<D2<<") = "<<((N1*D2)<<"/"<<(D1*N2))<<" = "<<((N1*D2)/(D1*N2))<<endl;

I have to submit this as an assignment.

This is my Desired Interface. Note: This is made using cout statements, there is no computing in the back-end.

Answer 1

check your parentheses:

cout<<"Addition of Given Fraction is: ("<<N1<<"/"<<D1<<") + ("<<N2<<"/"<<D2<<") = "
<<(((N1*D2)+(N2*D1))<<"/"<<(D1*D2))<<" = "<<(((N1*D2)+(N2*D1))/(D1*D2))<<endl;
  ^                               ^                     

Try this:

    case '+':
        cout<<"Addition of Given Fraction is: ("<<N1<<"/"<<D1<<") + ("<<N2<<"/"<<D2<<") = "<<((N1*D2)+(N2*D1))<<"/"<<(D1*D2)<<" = "<<(((N1*D2)+(N2*D1))/(D1*D2))<<endl;
        break;

    case '-':
        cout<<"Subtraction of Given Fraction is: ("<<N1<<"/"<<D1<<") - ("<<N2<<"/"<<D2<<") = "<<((N1*D2)-(N2*D1))<<"/"<<(D1*D2)<<" = "<<(((N1*D2)-(N2*D1))/(D1*D2))<<endl;
        break;

    case '*':
        cout<<"Multiplication of Given Fraction is: ("<<N1<<"/"<<D1<<") * ("<<N2<<"/"<<D2<<") = "<<(N1*N2)<<"/"<<(D1*D2)<<" = "<<((N1*N2)/(D1*D2))<<endl;
        break;

    case '/':
        cout<<"Division of Given Fraction is: ("<<N1<<"/"<<D1<<") / ("<<N2<<"/"<<D2<<") = "<<(N1*D2)<<"/"<<(D1*N2)<<" = "<<((N1*D2)/(D1*N2))<<endl;
        break;