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Description
Type of issue
Code doesn't work
Description
In the current documentation, there's a code sample that doesn't work as intended. The issue is in the following method:
private static Dictionary<string, int> CountWords(ReadOnlySpan<char> input)
{
Dictionary<string, int> wordCounts = new(StringComparer.OrdinalIgnoreCase);
Dictionary<string, int>.AlternateLookup<ReadOnlySpan<char>> spanLookup =
wordCounts.GetAlternateLookup<ReadOnlySpan<char>>();
foreach (Range wordRange in Regex.EnumerateSplits(input, @"\b\w+\b"))
{
ReadOnlySpan<char> word = input[wordRange];
spanLookup[word] = spanLookup.TryGetValue(word, out int count) ? count + 1 : 1;
}
return wordCounts;
}The problem is that Regex.EnumerateSplits is used to iterate over the input, but this method enumerates the separators between words, not the words themselves.
I believe the correct implementation should use Regex.EnumerateMatches instead, like this:
static Dictionary<string, int> CountWords(ReadOnlySpan<char> input)
{
Dictionary<string, int> wordCounts = new(StringComparer.OrdinalIgnoreCase);
Dictionary<string, int>.AlternateLookup<ReadOnlySpan<char>> spanLookup =
wordCounts.GetAlternateLookup<ReadOnlySpan<char>>();
foreach (ValueMatch match in Regex.EnumerateMatches(input, @"\b\w+\b"))
{
Range wordRange = match.Index..(match.Index + match.Length);
ReadOnlySpan<char> word = input[wordRange];
spanLookup[word] = spanLookup.TryGetValue(word, out int count) ? count + 1 : 1;
}
return wordCounts;
}This change ensures that the method correctly iterates over the words in the input, rather than the spaces between them.
Page URL
Content source URL
https://github.com/dotnet/docs/blob/main/docs/core/whats-new/dotnet-9/libraries.md
Document Version Independent Id
0c8c7059-86a1-e5df-32e6-fae6fdc5cae0
Article author
Metadata
- ID: 7c184200-3411-aa5b-ba3f-0b4a3ce0f589
- Service: dotnet-fundamentals