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Manual Reference Pages  - ISLOWER (P)

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islower - test for a lowercase letter

CONTENTS

Synopsis
Description
Return Value
Errors
Examples
     Testing for a Lowercase Letter
Application Usage
Rationale
Future Directions
See Also
Copyright

#include <ctype.h>

int islower(int c);

The islower() function shall test whether c is a character of class lower in the program’s current locale; see the Base Definitions volume of IEEE Std 1003.1-2001, Chapter 7, Locale.

The c argument is an int, the value of which the application shall ensure is a character representable as an unsigned char or equal to the value of the macro EOF. If the argument has any other value, the behavior is undefined.

The islower() function shall return non-zero if c is a lowercase letter; otherwise, it shall return 0.

No errors are defined.

The following sections are informative.

The following example tests whether the value is a lowercase letter, based on the locale of the user, then uses it as part of a key value.

#include <ctype.h>
#include <stdlib.h>
#include <locale.h>
...
char *keystr;
int elementlen, len;
char c;
...
setlocale(LC_ALL, "");
...
len = 0;
while (len < elementlen) {
    c = (char) (rand() % 256);
...
    if (islower(c))
        keystr[len++] = c;
    }
...

To ensure applications portability, especially across natural languages, only this function and those listed in the SEE ALSO section should be used for character classification.

None.

None.

isalnum() , isalpha() , iscntrl() , isdigit() , isgraph() , isprint() , ispunct() , isspace() , isupper() , isxdigit() , setlocale() , the Base Definitions volume of IEEE Std 1003.1-2001, Chapter 7, Locale, <ctype.h>

Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. In the event of any discrepancy between this version and the original IEEE and The Open Group Standard, the original IEEE and The Open Group Standard is the referee document. The original Standard can be obtained online at http://www.opengroup.org/unix/online.html .

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