The Open Group Base Specifications Issue 6
IEEE Std 1003.1, 2003 Edition
Copyright © 2001-2003 The IEEE and The Open Group, All Rights reserved.

NAME

stderr, stdin, stdout - standard I/O streams

SYNOPSIS

#include <stdio.h>

extern FILE *stderr, *stdin, *stdout;

DESCRIPTION

[CX] [Option Start] The functionality described on this reference page is aligned with the ISO C standard. Any conflict between the requirements described here and the ISO C standard is unintentional. This volume of IEEE Std 1003.1-2001 defers to the ISO C standard. [Option End]

A file with associated buffering is called a stream and is declared to be a pointer to a defined type FILE. The fopen() function shall create certain descriptive data for a stream and return a pointer to designate the stream in all further transactions. Normally, there are three open streams with constant pointers declared in the <stdio.h> header and associated with the standard open files.

At program start-up, three streams shall be predefined and need not be opened explicitly: standard input (for reading conventional input), standard output (for writing conventional output), and standard error (for writing diagnostic output). When opened, the standard error stream is not fully buffered; the standard input and standard output streams are fully buffered if and only if the stream can be determined not to refer to an interactive device.

[CX] [Option Start] The following symbolic values in <unistd.h> define the file descriptors that shall be associated with the C-language stdin, stdout, and stderr when the application is started:

STDIN_FILENO
Standard input value, stdin. Its value is 0.
STDOUT_FILENO
Standard output value, stdout. Its value is 1.
STDERR_FILENO
Standard error value, stderr. Its value is 2.

The stderr stream is expected to be open for reading and writing. [Option End]

RETURN VALUE

None.

ERRORS

No errors are defined.


The following sections are informative.

EXAMPLES

None.

APPLICATION USAGE

None.

RATIONALE

None.

FUTURE DIRECTIONS

None.

SEE ALSO

fclose() , feof() , ferror() , fileno() , fopen() , fread() , fseek() , getc() , gets() , popen() , printf() , putc() , puts() , read() , scanf() , setbuf() , setvbuf() , tmpfile() , ungetc() , vprintf() , the Base Definitions volume of IEEE Std 1003.1-2001, <stdio.h>, <unistd.h>

CHANGE HISTORY

First released in Issue 1.

Issue 6

Extensions beyond the ISO C standard are marked.

A note that stderr is expected to be open for reading and writing is added to the DESCRIPTION.

End of informative text.


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