Programmers use the ternary operator for decision making in place of longer if and else conditional statements.

The ternary operator take three arguments:

1. The first is a comparison argument
2. The second is the result upon a true comparison
3. The third is the result upon a false comparison

It helps to think of the ternary operator as a shorthand way or writing an if-else statement. Here’s a simple decision-making example using if and else:

int a = 10, b = 20, c;

if (a < b) {
c = a;
}
else {
c = b;
}

printf("%d", c);

This example takes more than 10 lines, but that isn’t necessary. You can write the above program in just 3 lines of code using a ternary operator.

Syntax

condition ? value_if_true : value_if_false

The statement evaluates to value_if_true if condition is met, and value_if_false otherwise.

Here’s the above example rewritten to use the ternary operator:

int a = 10, b = 20, c;

c = (a < b) ? a : b;

printf("%d", c);

Output of the example above should be:

10

c is set equal to a, because the condition a < b was true.

Remember that the arguments value_if_true and value_if_false must be of the same type, and they must be simple expressions rather than full statements.

Ternary operators can be nested just like if-else statements. Consider the following code:

int a = 1, b = 2, ans;
if (a == 1) {
if (b == 2) {
ans = 3;
} else {
ans = 5;
}
} else {
ans = 0;
}
printf ("%d\n", ans);

Here's the code above rewritten using a nested ternary operator:

int a = 1, b = 2, ans;
ans = (a == 1 ? (b == 2 ? 3 : 5) : 0);
printf ("%d\n", ans);

The output of both sets of code above should be:

3