Use Regex.Count
Use Regex.Count
Microsoft docsDescription
System.Text.RegularExpressions.Regex.Count is simpler and faster than Regex.Matches(...).Count. The Count() method is optimized for counting matches without materializing the full System.Text.RegularExpressions.MatchCollection. Calling Matches() and then accessing .Count does unnecessary work that can impact performance.
Cause
The System.Text.RegularExpressions.MatchCollection.Count property of the MatchCollection from System.Text.RegularExpressions.Regex.Matches is used to get the count of matches.
How to fix violations
Replace calls to Regex.Matches(...).Count with Regex.Count(...).
A *code fix* that automatically performs this transformation is available.
Example
using System.Text.RegularExpressions;
class Example
{
public int CountWords(string text)
{
// Violation
return Regex.Matches(text, @"\b\w+\b").Count;
}
}
using System.Text.RegularExpressions;
class Example
{
public int CountWords(string text)
{
// Fixed
return Regex.Count(text, @"\b\w+\b");
}
}When to suppress
It's safe to suppress a warning from this rule if performance isn't a concern or if you're targeting a version of .NET that doesn't include Regex.Count (prior to .NET 7).