### C Library Functions: Character Case Mapping

Function | Header File | Description
strlwr | string.h | Converts any uppercase letters in a string to lowercase.
strupr | string.h | Converts any lowercase letters in a string to uppercase.
_toascii | ctype.h | Converts a value to its ASCII character equivalent.
tolower | ctype.h | Converts a character to lowercase.
_tolower | ctype.h | Converts an uppercase ASCII character to lowercase.
toupper | ctype.h | Converts a character to uppercase.
_toupper | ctype.h | Converts a lowercase ASCII character to uppercase.
towctrans | wctype.h | Performs wide-character mapping using wctrans.**
towlower | wctype.h | Converts an uppercase wide character to a lowercase.
towupper | wctype.h | Converts a lowercase wide character to uppercase.
wctrans | wctype.h | Describes a wide-character mapping.**

Alphabetical Listing of IBM C and C++ Compilers Functions and Macros