C++ Conditional ? : Operator


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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

cpp_operators.htm

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