review code for “Best practices for comparing strings in .NET”

[BryanWilhite]

🔗 https://learn.microsoft.com/en-us/dotnet/standard/base-types/best-practices-strings

[BryanWilhite]

Issue #158 leads us to “Best practices for comparing strings in .NET” and the following points that are relevant to [[Songhay Core (C♯)]]:

• Use overloads that explicitly specify the string comparison rules for string operations. Typically, this involves calling a method overload that has a parameter of type StringComparison.
• Use StringComparison.Ordinal or StringComparison.OrdinalIgnoreCase for comparisons as your safe default for culture-agnostic string matching.
• Use comparisons with StringComparison.Ordinal or StringComparison.OrdinalIgnoreCase for better performance.
• Use string operations that are based on StringComparison.CurrentCulture when you display output to the user. …
• Use the String.ToUpperInvariant method instead of the String.ToLowerInvariant method when you normalize strings for comparison.
• Use an overload of the String.Equals method to test whether two strings are equal. …
• Don't use string operations based on StringComparison.InvariantCulture in most cases. One of the few exceptions is when you're persisting linguistically meaningful but culturally agnostic data.

Observations

• [[Songhay Core (C♯)]] uses StringComparison.OrdinalIgnoreCase more than any other comparison type.
• I think Songhay.Extensions.StringExtensions.EqualsInvariant is correct with respect to this context.
• Almost all *.IndexOf calls in [[Songhay Core (C♯)]] is for Array.IndexOf which has no overloads for string comparison.
• Songhay.Extensions.StringExtensions.ToSubstringInContext uses String.IndexOf with StringComparison.Ordinal.
• Songhay.Xml.HtmlUtility.EvaluateOpenElement uses String.IndexOf with StringComparison.OrdinalIgnoreCase.
• String.Compare is not explicitly used in [[Songhay Core (C♯)]].
• String.ToLowerInvariant is not used in any comparison operations—it is used only to format for display.