string-comparison edge case culture.cs

string-comparison.cs

// https://www.meziantou.net/string-comparisons-are-harder-than-it-seems.htm

Console.WriteLine("The current culture is {0}",
						  Thread.CurrentThread.CurrentCulture.Name);

//Thread.CurrentThread.CurrentCulture = new CultureInfo("tr-TR");
//// Change the current culture to Portuguese (Brazil).
//Console.WriteLine("Current culture changed to {0}",
//				  Thread.CurrentThread.CurrentCulture.Name);
			  

CultureInfo.CurrentCulture = new CultureInfo("tr-TR"); // Turkish
string.Equals("i", "I", StringComparison.CurrentCultureIgnoreCase).Dump(); // false
string.Equals("i", "İ", StringComparison.CurrentCultureIgnoreCase).Dump(); // true
string.Equals("i", "İ", StringComparison.OrdinalIgnoreCase).Dump(); // false
string.Equals("i", "İ", StringComparison.CurrentCulture).Dump(); // false
string.Equals("i", "I", StringComparison.OrdinalIgnoreCase).Dump(); // true

CultureInfo.CurrentCulture = new CultureInfo("de-DE"); // german
string.Equals("ss", "ß", StringComparison.OrdinalIgnoreCase).Dump();          // false
string.Equals("ss", "ß", StringComparison.InvariantCulture).Dump();           // true on Windows / false on Linux (WSL)
string.Equals("ss", "ß", StringComparison.InvariantCultureIgnoreCase).Dump();
string.Equals("æ", "ae", StringComparison.Ordinal).Dump();          // false
string.Equals("æ", "ae", StringComparison.InvariantCulture).Dump(); // true


CultureInfo.CurrentCulture = CultureInfo.GetCultureInfo("hu-HU");
"endz".Contains("z", StringComparison.CurrentCulture).Dump();  // False
"endz".Contains("d", StringComparison.CurrentCulture).Dump();  // False
"endz".Contains("dz", StringComparison.CurrentCulture).Dump(); // True
"d".Contains("d", StringComparison.CurrentCulture).Dump();  // True
"z".Contains("z", StringComparison.CurrentCulture).Dump();  // True


CultureInfo.CurrentCulture = new CultureInfo("th_TH.UTF8");
string.Equals("1", "๑", StringComparison.CurrentCulture);             // true
string.Equals("1", "๑", StringComparison.InvariantCultureIgnoreCase); // false