C# - Ternary Operator ?:

Updated on: June 24, 2020

C# includes a decision-making operator ?: which is called the conditional operator or ternary operator. It is the short form of the if else conditions.

Syntax:

condition ? statement 1 : statement 2

The ternary operator starts with a boolean condition. If this condition evaluates to true then it will execute the first statement after ?, otherwise the second statement after : will be executed.

The following example demonstrates the ternary operator.

Example: Ternary operator

int x = 20, y = 10;

var result = x > y ? "x is greater than y" : "x is less than y";

Console.WriteLine(result);

Try it

output:

x is greater than y

Above, a conditional expression x > y returns true, so the first statement after ? will be execute.

The following executes the second statement.

Example: Ternary operator 

                int x = 10, y = 100;

var result = x > y ? "x is greater than y" : "x is less than y";

Console.WriteLine(result);

output:

x is less than y

Thus, a ternary operator is short form of if else statement. The above example can be re-write using if else condition, as shown below.

Example: Ternary operator replaces if statement

int x = 10, y = 100;

if (x > y)
    Console.WriteLine("x is greater than y");
else
    Console.WriteLine("x is less than y");

Try it

output:

x is greater than y

Nested Ternary Operator

Nested ternary operators are possible by including a conditional expression as a second statement.

Example: Nested ?:

                int x = 10, y = 100;

string result = x > y ? "x is greater than y" : 
                    x < y ? "x is less than y" : 
                        x == y ? "x is equal to y" : "No result";

Console.WriteLine(result);

Try it

The ternary operator is right-associative. The expression a ? b : c ? d : e is evaluated as a ? b : (c ? d : e), not as (a ? b : c) ? d : e.

Example: Nested ?:

var x = 2, y = 10;

var result = x * 3 > y ? x : y > z? y : z;
Console.WriteLine(result);

Try it