Returns string with all alphabetic characters converted to uppercase.
The string being uppercased.
The encoding parameter is the character encoding. If it is omitted or null, the internal character encoding value will be used.
string with all alphabetic characters converted to uppercase.
By contrast to strtoupper, 'alphabetic' is determined by the Unicode character properties. Thus the behaviour of this function is not affected by locale settings and it can convert any characters that have 'alphabetic' property, such as a-umlaut (ä).
For more information about the Unicode properties, please see http://www.unicode.org/reports/tr21/.