Char.ToLowerInvariant Method (Char)
Converts the value of a Unicode character to its lowercase equivalent using the casing rules of the invariant culture.
Assembly: mscorlib (in mscorlib.dll)
If your application is unaffected by the current culture and depends on the case of a character changing in a predictable way, then use the ToLower(Char, CultureInfo.InvariantCulture).method. The method is equivalent to
Use String.ToLowerInvariant to convert a string to lowercase.
Available since 4.5
Available since 2.0
Portable Class Library
Supported in: portable .NET platforms
Available since 4.0
Windows Phone Silverlight
Available since 7.0
Available since 8.1