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