Converts the value of a Unicode character to its uppercase equivalent using the casing rules of the invariant culture.
The uppercase equivalent of the c parameter, or the unchanged value of c, if c is already uppercase or not alphabetic.
If your application is unaffected by the current culture and depends on the case of a character changing in a predictable way, use the char.ToUpperInvariant(char) method. The char.ToUpperInvariant(char) method is equivalent to ToUpper(Char, CultureInfo.InvariantCulture).
Use string.ToUpperInvariant to convert a string to uppercase.