un

Algorithms for Image Processing and Computer Vision Source Code

@c ----------------------------------------------------------------------
@node ungetc, stdio
@heading @code{ungetc}
@subheading Syntax

@example
#include <stdio.h>

int ungetc(int c, FILE *file);
@end example

@subheading Description

This function pushes @var{c} back into the @var{file}.  You can only
push back one character at a time. 

@subheading Return Value

The pushed-back character, or @code{EOF} on error.

@subheading Example

@example
int q;
while (q = getc(stdin) != 'q');
ungetc(q);
@end example

@c ----------------------------------------------------------------------
@node unlink, file system
@heading @code{unlink}
@subheading Syntax

@example
#include <osfcn.h>

int unlink(const char *file);
@end example

@subheading Description

This function removes a file from the file system. 

@subheading Return Value

Zero on success, nonzero on failure. 

@subheading Example

@example
unlink("data.txt");
@end example

@c ----------------------------------------------------------------------
@node unlock, io
@heading @code{unlock}
@subheading Syntax

@example
#include <io.h>

int unlock(int fd, long offset, long length);
@end example

@subheading Description
Unlocks a region previously locked by @code{lock}.

@xref{lock}.

@subheading Return Value
Zero if successful, nonzero if not.

@c ----------------------------------------------------------------------
@node unsetenv, environment
@heading @code{unsetenv}
@subheading Syntax

@example
#include <stdlib.h>

void unsetenv(const char *name);
@end example

@subheading Description

This function removes the given environment variable from the
environment. 

@subheading Return Value

None.

@subheading Example

@example
unsetenv("TERM");
@end example