C# 3.0 Cookbook, 3rd Edition

2.2. Controlling Case Sensitivity When Comparing Two Characters

Problem

You need to compare two characters for equality, but you need the flexibility of performing a case-sensitive or case-insensitive comparison.

Solution

Create extension methods on the char type and use the Equals instance method on the char structure to compare the two characters:

	static class CharStrExtMethods
	{
	    public static bool IsCharEqual(this char firstChar, char secondChar)
	    {
	        return (IsCharEqual(firstChar, secondChar, false));
	    }

	    public static bool IsCharEqual(this char firstChar, char secondChar,
	                                   bool caseSensitiveCompare)
	    {
	        if (caseSensitiveCompare)
	        {
	            return (firstChar.Equals(secondChar));
	        }
	        else
	        {
	            return (char.ToUpperInvariant(firstChar).Equals(
	                             char.ToUpperInvariant(secondChar)));
	        }
	    }
	public static bool IsCharEqual(this char firstChar, CultureInfo firstCharCulture,
	                                  char secondChar, CultureInfo secondCharCulture)
	   {
	       return (IsCharEqual(firstChar, firstCharCulture,
	               secondChar, secondCharCulture, false));
	   }
	public static bool IsCharEqual(this char firstChar, CultureInfo firstCharCulture,
	                                  char secondChar, CultureInfo secondCharCulture,
	                                  bool caseSensitiveCompare)
	   {
	       if (caseSensitiveCompare)
	       {
	           return (firstChar.Equals(secondChar));
	       }
	       else
	       {
	           return (char.ToUpper(firstChar, firstCharCulture).Equals
	                   (char.ToUpper(secondChar, secondCharCulture)));
	       }
	   }
	}

The first overloaded IsCharEqual extension method takes only one parameter, which is the character to be compared against the value contained in the current char instance. ...