NAME

getwc(), getwchar(), fgetwc() − get a wide character from a stream file

SYNOPSIS

#include <wchar.h>

wint_t getwc(FILE *stream);

wint_t getwchar(void);

wint_t fgetwc(FILE *stream);

Remarks:

These functions are compliant with the XPG4 Worldwide Portability Interface wide-character I/O functions.  They parallel the 8 bit character I/O functions defined in getc(3S).

DESCRIPTION

getwc() Returns the next character from the named input stream, converts that to the corresponding wide character and moves the file pointer ahead one character in stream. getwchar() is defined as getwc(stdin).  getwc() and getwchar() are defined both as macros and as functions. 

fgetwc() Behaves like getwc(), but is a function rather than a macro. 

Definitions for these functions, the types wint_t, wchar_t and the value WEOF are provided in header file <wchar.h>. 

RETURN VALUE

Upon successful completion, getwc(), getwchar(), and fgetwc() return the next wide character read from stream (stdin for getwchar()) converted to a type wint_t.  If the stream is at end-of-file, the end-of-file indicator for the stream is set and WEOF is returned.  If a read error occurs, the error indicator for the stream is set, errno is set to indicate the error, and WEOF is returned. 

ferror() and feof() can be used to distinguish between an error condition and an end-of-file condition. 

ERRORS

getwc(), getwchar(), and fgetwc() fail if data needs to be read into the stream’s buffer, and:

[EAGAIN] The O_NONBLOCK flag is set for the file descriptor underlying stream and the process would be delayed in the read operation. 

[EBADF] The file descriptor underlying stream is not a valid file descriptor open for reading. 

[EINTR] The read operation was terminated due to the receipt of a signal, and either no data was transferred or the implementation does not report partial transfer for this file. 

[EIO] The process is a member of a background process and is attempting to read from its controlling terminal, and either the process is ignoring or blocking the SIGTTIN signal or the process group of the process is orphaned. 

[EILSEQ] The data obtained from the input stream does not form a valid wide character. 

Additional errno values may be set by the underlying read() function (see read(2)).

EXTERNAL INFLUENCES

Locale

The LC_CTYPE category determines how wide character conversions are done. 

International Code Set Support

Single- and multi-byte character code sets are supported. 

WARNINGS

getwc() and getwchar() are implemented both as library functions and macros.  The macro versions, which are used by default, are defined in <wchar.h>.  To obtain the library function, either use a #undef to remove the macro definition or, if compiling in ANSI-C mode, enclose the function name in parenthesis or use the function address.  The following example illustrates each of these methods :

#include <wchar.h>
#undef getwc
...
main()
{
    wint_t (*get_wchar()) ();
...
    return_val=getwc(c,fd);
...
    return_val=(getwc)(c,fd1);
...
    get_wchar = getwchar;
};

If the value returned by getwc(), getwchar(), or fgetwc() is stored into a type wchar_t variable then compared against the constant WEOF, the comparison may never succeed because extension of a wchar_t to a wint_t is machine-dependent. 

The macro version of getwc() incorrectly treats a stream argument with side effects.  In particular, getwc(*f++) does not work sensibly.  The function version of getwc() or fgetwc() should be used instead. 

SEE ALSO

fclose(3S), ferror(3S), fopen(3S), fread(3S), fgetws(3C), putwc(3C), read(2), scanf(3S). 

STANDARDS CONFORMANCE

getwc(): XPG4

fgetwc(): XPG4

getwchar(): XPG4

Hewlett-Packard Company  —  HP-UX Release 9.0: August 1992