getc.3s

unix v7是最后一个广泛发布的研究型UNIX版本

.TH GETC 3S 
.SH NAME
getc, getchar, fgetc, getw \- get character or word from stream
.SH SYNOPSIS
.B #include <stdio.h>
.PP
.B int getc(stream)
.br
.SM
.B FILE
.B *stream;
.PP
.B int getchar()
.PP 
.B int fgetc(stream)
.br
.SM
.B FILE
.B *stream;
.PP
.B int getw(stream)
.br
.SM
.B FILE
.B *stream;
.SH DESCRIPTION
.I Getc
returns the next character from the named input
.IR stream .
.PP
.I Getchar()
is identical to 
.IR getc(stdin) .
.PP
.I Fgetc
behaves like 
.I getc,
but is a genuine function, not a macro;
it may be used to save object text.
.PP
.I Getw
returns the next
word from the named input
.IR stream .
It returns the constant
.SM
.B EOF
upon end of file or error, but since that is a good
integer value,
.I feof
and
.IR  ferror (3)
should be used to check the success of
.IR getw .
.I Getw
assumes no special alignment in the file.
.SH "SEE ALSO"
fopen(3), putc(3),
gets(3), scanf(3),
fread(3),
ungetc(3)
.SH DIAGNOSTICS
These functions return the integer constant
.SM
.B EOF
at end of file or upon read error.
.PP
A stop with message,
`Reading bad file', means an attempt has been made to
read from a stream that has not been opened for
reading by
.IR fopen .
.SH BUGS
The end-of-file return from
.I getchar
is incompatible with that in UNIX editions 1-6.
.PP
Because it is implemented as a macro,
.I getc
treats a
.I stream
argument with side effects incorrectly.
In particular,
`getc(*f++);'
doesn't work sensibly.