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76 lines
1.6 KiB
Markdown
76 lines
1.6 KiB
Markdown
---
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title: Null-coalescing Operator
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---
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# Null-coalescing Operator
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The null-coalescing operator in C# is used to help assign one variable to another and specify an alternate value if the source value is `null`. The null-coalescing operator in C# is `??`.
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## Example 1
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Since `name` is `null`, `clientName` will be assigned the value "John Doe".
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```csharp
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string name = null;
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string clientName = name ?? "John Doe";
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Console.WriteLine(clientName);
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```
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```csharp
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> John Doe
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```
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## Example 2
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Since `name` is not `null`, `clientName` will be assigned the value of `name`, which is "Jane Smith".
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```csharp
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string name = "Jane Smith";
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string clientName = name ?? "John Doe";
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Console.WriteLine(clientName);
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```
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```csharp
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> Jane Smith
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```
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## Alternative to if...else Statement
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You could use an `if...else` statement to test for the presence of `null` and assign a different value.
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```csharp
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string clientName;
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if (name != null)
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clientName = name;
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else
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clientName = "John Doe";
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```
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However, this can be greatly simplified using the null-coalescing operator.
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```csharp
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string clientName = name ?? "John Doe";
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```
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## Alternative to Conditional (Ternary) Operator
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It is also possible to use the conditional operator to test for the presence of `null` and assign a different value.
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```csharp
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string clientName = name != null ? name : "John Doe";
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```
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Again, this can be simplified using the null-coalescing operator.
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```csharp
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string clientName = name ?? "John Doe";
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```
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## References
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* [?? Operator (C# Reference)](https://docs.microsoft.com/en-us/dotnet/csharp/language-reference/operators/null-conditional-operator) |