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<TITLE>ungetc</TITLE>
<body bgcolor="#ffffcc">
<hr>
<pre>
<h3>GETS(3) Linux Programmer's Manual GETS(3)
</h3>
<h3>NAME
</h3> fgetc, fgets, getc, getchar, gets, ungetc - input of char-
acters and strings
<h3>SYNOPSIS
</h3> #include <stdio.h>
int fgetc(FILE *stream);
char *fgets(char *s, int size, FILE *stream);
int getc(FILE *stream);
int getchar(void);
char *gets(char *s);
int ungetc(int c, FILE *stream);
<h3>DESCRIPTION
</h3> fgetc() reads the next character from stream and returns
it as an unsigned char cast to an int, or EOF on end of
file or error.
getc() is equivalent to fgetc() except that it may be
implemented as a macro which evaluates stream more than
once.
getchar() is equivalent to getc(stdin).
gets() reads a line from stdin into the buffer pointed to
by s until either a terminating newline or EOF, which it
replaces with '\0'. No check for buffer overrun is per-
formed (see BUGS below).
fgets() reads in at most one less than n characters from
stream and stores them into the buffer pointed to by s.
Reading stops after an EOF or a newline. If a newline is
read, it is stored into the buffer. A '\0' is stored
after the last character in the buffer.
ungetc() pushes c back to stream, cast to unsigned char,
where it is available for subsequent read operations.
Pushed - back characters will be returned in reverse
order; only one pushback is guaranteed.
Calls to the functions described here can be mixed with
each other and with calls to other input functions from
the stdio library for the same input stream.
<h3>RETURN VALUES
</h3> fgetc(), getc() and getchar() return the character read as
an unsigned char cast to an int or EOF on end of file or
error.
gets() and fgets() return s on success, and NULL on end of
file or error.
ungetc() returns c on success, or EOF on error.
<h3>GNU April 4, 1993 1
</h3>
<h3>GETS(3) Linux Programmer's Manual GETS(3)
</h3>
<h3>CONFORMS TO
</h3> ANSI - C, POSIX.1
<h3>BUGS
</h3> Because it is impossible to tell without knowing the data
in advance how many characters gets() will read, and
because gets() will continue to store characters past the
end of the buffer, it is extremely dangerous to use. It
has been used to break computer security. Use fgets()
instead.
It is not advisable to mix calls to input functions from
the stdio library with low - level calls to read() for the
file descriptor associated with the input stream; the
results will be undefined and very probably not what you
want.
</pre>
<hr>
<h3>SEE ALSO
</h3><p>
<a href=read.htm>read</a>,
<a href=write.htm>write</a>,
<a href=fopen.htm>fopen</a>,
<a href=fread.htm>fread</a>,
<a href=scanf.htm>scanf</a>,
<a href=puts.htm>puts</a>,
<a href=fseek.htm>fseek</a>,
<a href=ferror.htm>ferror</a>,
<pre>
<h3>GNU April 4, 1993 2
</h3>
</pre>
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