Consider using
.TryGetValue to access elements in Dictionary CS-P1005
Performance
Major
a month ago
—
2 years old
Double access to
Dictionary transformers27 // CS-P1005: Double access to `Dictionary`. First via `ContainsKey`, then via `Indexer`.
28 // Use `.TryGetValue` instead.
29 // https://deepsource.io/directory/analyzers/csharp/issues/CS-P1005
30 if (transformers.ContainsKey("csharp"))31 {
32 Console.WriteLine($"C#'s transformer is {transformers["csharp"]}");
33 }
Description
The .ContainsKey method allows you to check if a key exists in a Dictionary while the indexer, i.e. [] allows you to directly access the specified key's value. Using both of them means that you'd be effectively accessing the Dictionary twice. As an alternative, you can use .TryGetValue to get a value from a Dictionary that returns a bool depending on whether the key exists or not.
Bad Practice
if (dict.ContainsKey(key)) // 1st access to `dict`
Console.WriteLine(dict[key]); // 2nd access to `dict`
Recommended
if (dict.TryGetValue(key, out var val))
Console.WriteLine(val);