I cannot understand the compiler C switch, invalid operand error-CodePudding

#include <iostream>
#include <cmath>
using namespace std;

int main()
{
    float Litr;
    int opcja;

    cout << "Konwerter" << endl;
    switch(opcja){

case 1:
    cout << "Litr na barylke amerykanska i galon amerykanski" << endl;
    cin >> Litr;
    cout << Litr << " litrow to " << Litr * 159 << " barylek i " << Litr * 3,78 << "galonow.";
    break;
    }
    return 0;
}

Error in line 16 (e.g cout << Litr << " litrow to " << Litr * 159 << " barylek i " << Litr * 3,78 << "galonow."; )

||=== Build: Debug in aeiou (compiler: GNU GCC Compiler) ===| C:\Users*file loaction*\main.cpp|16|error: invalid operands of types 'int' and 'const char [9]' to binary 'operator<<'| ||=== Build failed: 1 error(s), 0 warning(s) (0 minute(s), 0 second(s)) ===|

Don't understand what's wrong and what compiler tries to tell me.

CodePudding user response：

You have a comma in 3,78 should be 3.78

See here for an example based on your code

CodePudding user response：

In this case, they are simple syntactic errors. When you have to express a decimal number in C you have to use the "." and not the ",". There was also the problem that the command to execute was not asked in input and a simple cin was inserted.

#include <iostream>

using namespace std;

int main() {
    int opcja;
    
    cout << "Konwerter: ";
    cin >> opcja;
    
    switch(opcja) {
        case 1: {
            float Litr;
            cout << "Litr na barylke amerykanska i galon amerykanski" << endl;
            cin >> Litr;
            cout << Litr << " litrow to " << Litr * 159 << " barylek i " << Litr * 3.78 << "galonow.";
            break;
        }
    }

    return 0;
}