isascii - Man Page

test for a 7-bit US-ASCII character


This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.


#include <ctype.h>

int isascii(int c);


The isascii() function shall test whether c is a 7-bit US-ASCII character code.

The isascii() function is defined on all integer values.

Return Value

The isascii() function shall return non-zero if c is a 7-bit US-ASCII character code between 0 and octal 0177 inclusive; otherwise, it shall return 0.


No errors are defined.

The following sections are informative.



Application Usage

The isascii() function cannot be used portably in a localized application.



Future Directions

The isascii() function may be removed in a future version.

See Also

The Base Definitions volume of POSIX.1-2017, <ctype.h>

Referenced By

ctype.h(0p), localeconv(3p), toascii(3p).

2017 IEEE/The Open Group POSIX Programmer's Manual