Ternary operator is a compact conditional assignment.

It serves to set a value of a variable depending on a boolean expression or a boolean variable.

a = b ? c : d;

The expression above is same as:

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

The a, c and d variables must be of the same data type (or type of c and d must be convertible to type of a using automatic conversion). The b variable is boolean.

b, c or d do not have to be variables. They may be constants or expressions. a has to be a variable.