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?: Operator (C# Reference) |
07/20/2015 |
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e83a17f1-7500-48ba-8bee-2fbc4c847af4 |
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BillWagner |
wiwagn |
?: Operator (C# Reference)
The conditional operator (?:) returns one of two values depending on the value of a Boolean expression. Following is the syntax for the conditional operator.
condition ? first_expression : second_expression;
Remarks
The condition must evaluate to true or false. If condition is true, first_expression is evaluated and becomes the result. If condition is false, second_expression is evaluated and becomes the result. Only one of the two expressions is evaluated.
Either the type of first_expression and second_expression must be the same, or an implicit conversion must exist from one type to the other.
You can express calculations that might otherwise require an if-else construction more concisely by using the conditional operator. For example, the following code uses first an if statement and then a conditional operator to classify an integer as positive or negative.
int input = Convert.ToInt32(Console.ReadLine());
string classify;
// if-else construction.
if (input > 0)
classify = "positive";
else
classify = "negative";
// ?: conditional operator.
classify = (input > 0) ? "positive" : "negative"; The conditional 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.
The conditional operator cannot be overloaded.
Example
[!code-cscsRefOperators#41]
See Also
C# Reference
C# Programming Guide
C# Operators
if-else
?. and ?Operators
?? Operator