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.\"   Copyright (c) 1994-2006 Lars Wirzenius.  All rights reserved.
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.\" part of publib
.\" "@(#)publib-files:$Id: files.3,v 1.2 1994/02/03 17:33:58 liw Exp $"
.\"
.TH FILES 3pub "C Programmer's Manual" Publib "C Programmer's Manual"
.SH NAME
xgetaline, xfseek, xfopen, xfclose, getaline, fassert \- file
manipulation utilities
.SH SYNOPSIS
.nf
#include <files.h>
.sp 1
FILE *\fBxfopen\fR(const char *\fIfilename\fR, const char *\fImode\fR);
void \fBxfclose\fR(FILE *\fIfp\fR);
void \fBxfseek\fR(FILE *\fIfp\fR, long \fIoffset\fR, int \fIorigin\fR);
char *\fBgetaline\fR(FILE *\fIfp\fR);
char *\fBxgetaline\fR(FILE *\fIfp\fR);
void \fBfassert\fR(FILE *\fIfp\fR);
.SH "DESCRIPTION"
These functions are useful for file manipulation.  The functions that
begin with \fIx\fR work like the functions without the letter, except
if there is an error, they print an error message and kill the
program.
.PP
\fIgetaline\fR reads a line from the given file.  It allocates the
memory for the line with \fImalloc(3)\fR, and returns a pointer to the
beginning of the line.  If there is an error, it returns NULL.  If the
returned value is not NULL, the caller is responsible for freeing the
memory.  The newline is removed from the end of the line.
.PP
\fIfassert\fR checks that the argument is not NULL, and that (for a
non-NULL argument) the file does not have its error indicator flag
set.  If either condition is true, it prints an error message and
termiantes the program.   If neither condition is true, it does
nothing.  This can be used to add checks that the I/O in a program is
going well; however, it is mostly useful only for small programs,
because more serious programs need to handle the errors more
gracefully.
.SH "SEE ALSO"
publib(3)
.SH AUTHOR
Lars Wirzenius (lars.wirzenius@helsinki.fi)