Conditional operator(?:) in C#

Conditional operator (?:) in C# is used as a single line if-else assignment statement, it is also know as Ternary Operator in C# . It evaluates a boolean expression and on the basis of the evaluated True and False value executes corresponding statement.

Precisely, In C# Conditional operator (?:) can be explained as follows.

It has three operands : condition, consequence and alternative. The conditional expression returns a Boolean value as true or false . If the value is true, then it evaluates the consequence expression. If false, then it evaluates the alternative expression.

Syntax of conditional operator (?:) in C#

It uses a question mark ( ? ) operator and a colon ( : )  operator , the general format is as follows.

Condition (Boolean expression) ? consequence (if true) : alternative (if false)

Lets look at below example, here we are doing a conditional check and based on the true/false, assigning the variable value to taxPercentage .

In above case, If isSiniorCitizen == true then taxPercentage will be 20 else it will be 30, in the above case it sets to 20 since we have already set the boolean value isSiniorCitizen = true .

Example of (?:) operator in C#

Lets look at an example.

In above example code snippet, the boolean expression String.IsNullOrEmpty(LastName) returns True value, so the consequence statement executes, which gives output as “Ramesh” . 

Lets take another example, where conditional expression returns False value.

In above example, the boolean expression String.IsNullOrEmpty(LastName returns False value, so the alternative statement (FirstName + " " + LastName) executes, which gives output as “Ramesh Kumar”. 

Conditional operator(?:) vs Null Coalescing (??) Operator ?

In the case of Null coalescing operator (??), It checks for the null-ability of first operand and based on that assigns the value. If the first operand value is null then assigns second operand else assigns the first.

Lets have a look at below expression.

In the above example, If y is null then z will be assigned to x else y . For more details on Null coalescing operator (??), please check here. 

We can rewrite above expression using conditional operator (?:) as follows.

Here, if y is null (that means if the expression (Y == null) return true) then assign z else assign y to x .

In single line if else statement :

Lets take below if-else statement.

In above if-else statement, boolean expression determines variable assignment. This is the right scenario where we can use Conditional operator (?:) as a replacement of if-else statement.

In above example, here in this case i >= 5  is a True condition, hence 10 * 5  will be executed and 50 will be assigned to x. Lets take below example.

In above example, here condition i >= 5 is  False, hence 10 * 4  will be executed and 40 will be assigned to x.

Nested conditional operator (?:) in C#

In some scenarios, where there are cascading if-else conditions of variable assignment. We can use chaining conditional operators to replace cascading if-else conditions to a single line by including a conditional expression as a second statement.

Lets take below example of cascading/nested if-else statement.

Above cascading if-else condition can be re-written as follows.

Thanks for your time  feel free to provide your feedback and do check my other blogs on Null Coalescing Operator (??) in C#  and  Null-Conditional Operator in C# (?.)