Ternary operator

If-else constructs are generally pretty readable (they are english words, therefore self explanatory) but they come with the downside of being a bit too long to write (they also take a lot of vertical space in the code). This is the main reason why both C and C++ have a short-hand notation for writing if-else statements a lot quicker, called ternary operator.

Syntax

The general syntax of the ternary operator is as follows (it eventually returns a value so there's a variable result where to store it):

result = condition ? expressionIfTrue : expressionIfFalse;

where:

condition is any boolean expression;
expressionIfTrue is the code executed when the condition is satisfied;
expressionIfFalse is similar to what would be executed inside the else block when using a regular if-else construct.

The term "ternary" comes from the fact that this operator takes 3 operands, in this example condition, expressionIfTrue and expressionIfFalse.

Example:

ternary-operator.cpp
#include <iostream>
using namespace std;

int main() {
    int x, y;

    cout << "Insert x:" << endl;
    cin >> x;
    cout << "Insert y:" << endl;
    cin >> y;

    int result = (x > y) ? x : y; // store in result the largest number
    cout << "The largest number is: " << result << endl;

    return 0;
}

The code above is completely equivalent to the following using if-else:

int main() {
    // ...
    if (x > y) {
        result = x;
    } else {
        result = y;
    }
    cout << "The largest number is: " << result << endl;
    // ...
}

The result variable can be avoided by making two separate couts:

#include <iostream>
using namespace std;

int main() {
    int x, y;

    cout << "Insert x:" << endl;
    cin >> x;
    cout << "Insert y:" << endl;
    cin >> y;

    (x > y) ? cout << "x is the largest number" 
            : cout << "y is the largest number";

    return 0;
}

Syntax​

Syntax