HP C/iX Library Reference Manual (30026-90004)
370 Chapter5
HP C/iX Library Function Descriptions
tolower, _tolower
tolower, _tolower
Converts an uppercase letter to lowercase.
Syntax
#include <ctype.h>
int tolower (int
c
);
Parameters
c
An argument to be converted to lowercase.
Return Values
x The lowercase letter that corresponds with
c
. If
c
is not an uppercase
letter and the function is called,
c
is returned unchanged. If
c
is not an
uppercase letter and the macro is called, the results are undefined.
Description
This conversion routine that downshifts ASCII characters is implemented both as a
function and as a macro. The tolower function and _tolower macro have a domain the
range of getc() (the integers from -1 through 255). If the argument passed in
c
represents
an uppercase letter, tolower() returns the corresponding lowercase letter. All other
arguments in the domain are returned unchanged.
The _tolower macro accomplishes the same thing as the function, but has a restricted
domain and is faster. The _tolower macro requires a lowercase letter as its argument.
Arguments outside the domain cause undefined results.
NOTE
The tolower function and macro do not work with foreign character sets.
Example
The following code fragment might appear in the scanner of a case-insensitive compiler,
where all source input is mapped to lowercase before any processing is performed:
unsigned char *ps;
while (*ps != '\0'){
*ps = tolower(*ps);
&+&+ps;
}
See Also
toupper(), ANSI C 4.3.2.1, POSIX.1 8.1