C++ Conditional ? : Operator

 Exp1 ? Exp2 : Exp3; 

where Exp1, Exp2, and Exp3 are expressions. Notice the use and placement of the colon. The value of a ? expression is determined like this: Exp1 is evaluated. If it is true, then Exp2 is evaluated and becomes the value of the entire ? expression. If Exp1 is false, then Exp3 is evaluated and its value becomes the value of the expression.

The ? is called a ternary operator because it requires three operands and can be used to replace if-else statements, which have the following form −

 if(condition) { var = X; } else { var = Y; } 

For example, consider the following code −

 if(y < 10) { var = 30; } else { var = 40; } 

Above code can be rewritten like this −

 var = (y < 10) ? 30 : 40; 

Here, x is assigned the value of 30 if y is less than 10 and 40 if it is not. You can the try following example −

 #include <iostream> using namespace std; int main () { // Local variable declaration: int x, y = 10; x = (y < 10) ? 30 : 40; cout << "value of x: " << x << endl; return 0; } 

When the above code is compiled and executed, it produces the following result −

 value of x: 40