HP-UX Reference (11i v2 03/08) - 3 Library Functions A-M (vol 6)

ManualsBrandsHP ManualsSoftwareHP-UX Reference Manuals

401

402

403

404

405

406

407

408

409

410

getc(3S) getc(3S)

[EAGAIN] The O_NONBLOCK ﬂag is set for the ﬁle descriptor underlying stream and the pro-

cess 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] A physical I/O error has occurred, or the process is a member of a background pro-

cess 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.

Additional

errno values may be set by the underlying

read() function (see read(2)).

WARNINGS

getc() and getchar() are implemented both as library functions and macros. The macro versions,

which are used by default, are deﬁned in

<stdio.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 <stdio.h>

#undef getc

...

main()

{

int (*get_char()) ();

...

return_val=getc(c,fd);

...

return_val=(getc)(c,fd1);

...

get_char = getchar;

};

If the integer value returned by getc(), getc_unlocked()

, getchar(), getchar_unlocked(),

fgetc() is stored into a character variable then compared against the integer constant EOF, the com-

parison may never succeed because sign-extension of a character on widening to integer is machine-

dependent.

The macro version of

getc() incorrectly treats a stream argument with side effects. In particular,

getc(*f++) does not work sensibly. The function version of getc() or fgetc() should be used

instead.

Because of possible differences in word length and byte ordering, ﬁles written using

putw() are

machine-dependent, and may be unreadable by

getw() on a different processor.

Reentrant Interfaces

_REENTRANT is deﬁned before including <stdio.h>, the locked versions of the library functions for

getc() and getchar() are used by default.

getw_unlocked() is an obsolescent interface supported only for compatibility with existing DCE

applications. New multithreaded applications should use getw().