Guardian C Library Calls Reference Manual

Reference to Library Calls

Guardian TNS C Library Calls Reference Manual—128833 3-225

tolower

The tolower function determines the lowercase equivalent of an uppercase letter.

character

is the character whose lowercase equivalent you desire.

Return Value

is the lowercase equivalent of character.

Usage Guidelines

•

If character is not an uppercase letter, tolower simply returns it unchanged.

•

The character-testing routine tolower is implemented as a macro, but the C compiler

provides an underlying function with the same name as the macro. Although the

macro is faster than the function, it evaluates its argument more than once.

Consequently, if you need to provide an expression with side effects as the argument

to this routine, you should undefine the macro so that the C compiler uses the

function instead. For more information about undefining macros, refer to the C/C++

Programmer’s Guide.

#include <ctypeh>

int tolower(int character);