The ternary if-else is unusual because it has three operands. It is truly an operator because it produces a value, unlike the ordinary if-else statement. It consists of three expressions: if the first expression (followed by a ?) evaluates to true, the expression following the ? is evaluated and its result becomes the value produced by the operator. If the first expression is false, the third expression (following a :) is executed and its result becomes the value produced by the operator.

The conditional operator can be used for its side effects or for the value it produces. Here’s a code fragment that demonstrates both:

Here, the conditional produces the rvalue. a is assigned to the value of b if the result of decrementing b is nonzero. If b became zero, a and b are both assigned to -99. b is always decremented, but it is assigned to -99 only if the decrement causes b to become 0. A similar statement can be used without the “a =” just for its side effects:

Here the second B is superfluous, since the value produced by the operator is unused. An expression is required between the ? and :. In this case, the expression could simply be a constant that might make the code run a bit faster.