The ternary operator

Learn to write a conditional expression in one line with ? :.

The ternary operator

The ternary operator is a way to write a simple if/else on a single line. Its form is condition ? true_value : false_value and it produces a value.

For example: std::string result = (age >= 18) ? "Drive" : "Wait";. This does the same as a four-line if/else but is shorter in an assignment context. For complex conditions readability drops; then if/else is preferred.

Ternary in assignment

The ternary shines in assignment statements. Writing int max = (a > b) ? a : b; finds the larger of two numbers in one line. The same with if/else would take three or four lines.

Because the ternary produces a value, you can also use it directly as in std::cout << ((a > b) ? a : b). Nesting ternary expressions is possible but hurts readability, so it is usually avoided.

Exercise Find the larger number

The a and b variables are given. Use the ternary operator in the form int max = (a > b) ? a : b; to assign the larger one to max and print it with std::cout. The output must be 12.

Show example solution

#include <iostream>

int main() {
    int a = 7;
    int b = 12;
    int max = (a > b) ? a : b;
    std::cout << max << std::endl;
    return 0;
}

Test yourself

Write the ternary operator

std::string result = (age >= 18) ____ "Drive" : "Wait";

Show answer

std::string result = (age >= 18) ? "Drive" : "Wait";

Match each ternary part to its role

?

When condition is true
:

When condition is false
(age >= 18)

The condition
"Drive"

The true value
What is the result of (5 > 3) ? "yes" : "no"?
```
auto r = (5 > 3) ? "yes" : "no";
```
- "no"
- true
- 5
- "yes"
Show answer

"yes" — 5 > 3 is true, so the result is "yes".

Next lesson: Nested conditionals

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