CA1853: Unnecessary call to 'Dictionary.ContainsKey(key)'
Property | Value |
---|---|
Rule ID | CA1853 |
Title | Unnecessary call to 'Dictionary.ContainsKey(key)' |
Category | Performance |
Fix is breaking or non-breaking | Non-breaking |
Introduced version | .NET 7 |
Enabled by default in .NET 8 | As suggestion |
Cause
A call to Dictionary<TKey,TValue>.Remove(TKey) is guarded with a call to Dictionary<TKey,TValue>.ContainsKey(TKey).
Rule description
There's no need to guard Dictionary.Remove(key)
with Dictionary.ContainsKey(key)
. Dictionary<TKey,TValue>.Remove(TKey) already checks whether the key exists and doesn't throw if it doesn't exist.
How to fix violations
Remove the guarding code that calls Dictionary<TKey,TValue>.ContainsKey(TKey).
Example
The following code snippet shows a violation of CA1853:
Dictionary<string, int> d = new();
if (d.ContainsKey("name"))
d.Remove("name");
Class C
Shared Sub S()
Dim d As New Dictionary(Of String, Integer)
If d.ContainsKey("name") Then
d.Remove("name")
End If
End Sub
End Class
The following code snippet fixes the violation:
Dictionary<string, int> d = new();
d.Remove("name");
Class C
Shared Sub S()
Dim d As New Dictionary(Of String, Integer)
d.Remove("name")
End Sub
End Class
When to suppress warnings
It's safe to suppress a warning if performance isn't a concern.
Suppress a warning
If you just want to suppress a single violation, add preprocessor directives to your source file to disable and then re-enable the rule.
#pragma warning disable CA1853
// The code that's violating the rule is on this line.
#pragma warning restore CA1853
To disable the rule for a file, folder, or project, set its severity to none
in the configuration file.
[*.{cs,vb}]
dotnet_diagnostic.CA1853.severity = none
For more information, see How to suppress code analysis warnings.
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