C++ nested if statments, basic currency exchange

Question

I have a simple C++ issue with my if statements, the program runs the values as the initial if parameters rather than performing the else if. Also I tried to code so that if the result of the function equaled 1 it would type out a grammatically correct statement is there a better way of doing that other than using another if statement?

int main()
{
cout << "Please type out amount and currency type to convert to dollars.\n";
double val1;
string currency;
double result = 0;
cin >> val1 >> currency;
if (currency == "yen" || "y")
{
    result = val1/100;
    if (result == 1) {
        cout << "You have " << val1 << "yen which equals \n"
            << result << ", dollar.";
    }
    else
    cout << "You have " << val1 << "yen which equals \n"
        << result << ", dollars.";
}
else if (currency == "euros" || "e")
{
    result = val1*1.25;
    if (result == 1) {
        cout << "You have " << val1 << "euros which equals \n"
            << result << ", dollar.";
    }
    else
        cout << "You have " << val1 << "euros which equals \n"
        << result << ", dollars.";
}
else if (currency == "pounds" || "p")
{
    {
        result = val1 *1.2;
        if (result == 1) {
            cout << "You have " << val1 << "pounds which equals \n"
                << result << ", dollar.";
        }
        else
            cout << "You have " << val1 << "pounds which equals \n"
            << result << ", dollars.";
    }
}
else
    cout << "I didn't understand, please try again.\n";
}

Answer 1

When you type if (currency == "yen" || "y") , you probably want it to mean "if currency is equal to "yen" or if it is equal to "y" , do something".

However, this is not what your if-statement actually does. The if-statement

if (currency == "yen" || "y")

first tests if the string currency is equal to "yen" , and if not, it evaluates "y" by itself and checks if it is equal to true.

In this case, "y" will be truncated to a bool , meaning that it will evaluate to true (because "y" is not equal to 0 ). As a result, your first if-statement will always evaluate to true!

To fix this, replace your if-statement with if (currency == "yen" || currency == "y") .

---

For your second question, you could use a conditional operator, which works as so:

cout << "You have " << (val1 == 1? "thing": "things") << endl;

The conditional in this case is (val1 == 1? "thing": "things") . It checks if val1 == 1 , then returns "thing" if it is true and "things" otherwise.