ea3ad82654
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53 lines
1.5 KiB
Plaintext
53 lines
1.5 KiB
Plaintext
== Why is this an issue?
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https://learn.microsoft.com/en-us/dotnet/api/system.nullable-1[Nullable value types] can hold either a value or `null`.
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The value held in the nullable type can be accessed with the `Value` property or by casting it to the underlying type. Still, both operations throw an `InvalidOperationException` when the value is `null`. A nullable type should always be tested before accessing the value to avoid raising exceptions.
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== How to fix it
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=== Code examples
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==== Noncompliant code example
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[source,csharp,diff-id=1,diff-type=noncompliant]
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----
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void Sample(bool condition)
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{
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int? nullableValue = condition ? 42 : null;
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Console.WriteLine(nullableValue.Value); // Noncompliant: InvalidOperationException is raised
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int? nullableCast = condition ? 42 : null;
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Console.WriteLine((int)nullableCast); // Noncompliant: InvalidOperationException is raised
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}
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----
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==== Compliant solution
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[source,csharp,diff-id=1,diff-type=compliant]
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----
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void Sample(bool condition)
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{
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int? nullableValue = condition ? 42 : null;
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if (nullableValue.HasValue)
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{
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Console.WriteLine(nullableValue.Value);
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}
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int? nullableCast = condition ? 42 : null;
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if (nullableCast is not null)
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{
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Console.WriteLine((int)nullableCast);
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}
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}
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----
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== Resources
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=== Documentation
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* https://learn.microsoft.com/en-us/dotnet/api/system.nullable-1[Nullable<T>]
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* https://cwe.mitre.org/data/definitions/476[MITRE, CWE-476] - NULL Pointer Dereference
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include::../rspecator-dotnet.adoc[]
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