1.3 String Library

For further details, please follow this link to the “String Manipulation” section in the Lua 5.1 Reference Manual.

String routines lower and upper are not tailored to the current locale. The conversion of strings to upper and lower case letters operates only on the 26 letters of the Latin alphabet. This restriction also applies to the alphabetic matching patterns (%a, %l, %u, and %w) employed by the find, gmatch, and match functions.