April 17, 2008 TOLOWER 3

### NAME

tolower - upper case to lower case letter conversion

### LIBRARY

Standard C Library (libc, -lc)

### SYNOPSIS

```int` tolower(```int c`)

### DESCRIPTION

The tolower(``) function converts an upper-case letter to the corresponding lower-case letter.

### RETURN VALUES

If the argument is an upper-case letter, the tolower(``) function returns the corresponding lower-case letter if there is one; otherwise the argument is returned unchanged.

### SEE ALSO

ctype(3), isalnum(3), isalpha(3), isascii(3), iscntrl(3), isdigit(3), isgraph(3), islower(3), isprint(3), ispunct(3), isspace(3), isupper(3), isxdigit(3), stdio(3), toascii(3), toupper(3), ascii(7)

### STANDARDS

The tolower(``) function conforms to ANSI X3.159-1989 (``ANSI C89'') .

### CAVEATS

The argument to tolower(``) must be ```EOF` or representable as an otherwise, the behavior is undefined. See the CAVEATS section of ctype(3) for more details.