62 lines
1.6 KiB
Markdown
62 lines
1.6 KiB
Markdown
---
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title: Null-conditional Operator
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---
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# Null-conditional Operator
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Null-conditional operators allow for null checking with a minimal amount of code. For example, if you had
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an employee variable of type Employee with a property of type Address, you might do null checking as follows:
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```csharp
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Address address = null;
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if (employee != null)
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{
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address = employee.Address;
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}
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```
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You could use a standard conditional operator to make that check more concise:
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```csharp
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Address address = employee != null ? employee.Address : null;
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```
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However, in C# 6.0 null-conditional operators were introduced, so now the above line can simply
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be represented as follows:
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```csharp
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Address address = employee?.Address;
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```
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If employee is null, address will simply be assigned null, and no NullReferenceExeception will occur.
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This becomes more useful with deeper object graphs, as you can handle a chain of conditional member access.
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For example:
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```csharp
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string city = employee?.Address?.City;
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```
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Null-conditional operators are short-circuiting, so as soon as one check of conditional member access
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returns null, the rest do not take place.
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# Null-coalescing operator
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Another useful null-checking option is the null-coalescing operator. It returns the left-hand operand if the operand is not null; otherwise it returns the right hand operand.
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For example:
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```csharp
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public string GetStringValue()
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{
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return null;
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}
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// Display the value of s if s is NOT null. If x IS null, display the string "It was null."
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string x = GetStringValue();
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Console.WriteLine(x ?? "It was null.");
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// Result:
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"It was null."
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```
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