gno/usr.man/man3/scandir.3

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.\"     @(#)scandir.3	8.1 (Berkeley) 6/4/93
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.TH SCANDIR 3 "27 January 1997" GNO "Library Routines"
.SH NAME
.BR scandir ,
.BR alphasort
\- scan a directory
.SH SYNOPSIS
#include <sys/types.h>
.br
#include <dirent.h>
.sp 1
int
\fBscandir\fR (const char *\fIdirname\fR,
struct dirent ***\fInamelist\fR,
int (*\fIselect\fR) (struct dirent *),
int (*\fIcompar\fR) (const void *, const void *));
.sp 1
int
alphasort (const void *d1, const void *d2);
.sp 1
int
alphacasesort (const void *d1, const void *d2);
.SH DESCRIPTION
The
.BR scandir 
function
reads the directory
.I dirname
and builds an array of pointers to directory
entries using
.BR malloc (3).
It returns the number of entries in the array.
A pointer to the array of directory entries is stored in the location
referenced by
.IR namelist .
.LP
The
.I select
parameter is a pointer to a user supplied subroutine which is called by
.BR scandir 
to select which entries are to be included in the array.
The select routine is passed a
pointer to a directory entry and should return a non-zero
value if the directory entry is to be included in the array.
If
.I select
is null, then all the directory entries will be included.
.LP
The
.I compar
parameter is a pointer to a user supplied subroutine which is passed to
.BR qsort (3)
to sort the completed array.
If this pointer is null, the array is not sorted.
.LP
The
.BR alphasort 
function
is a routine which can be used for the
.I compar
parameter to sort the array alphabetically.
.LP
The
.BR alphacasesort
function is similar to 
.BR alphasort ,
but can be used for sorting in a case-insensitive manner, and is useful
for the case-insensitive filesystems used by GNO.  This function is
specific to GNO.
.LP
The memory allocated for the array can be deallocated with
.BR free (3),
by freeing each pointer in the array and then the array itself.
.SH DIAGNOSTICS
Returns \-1 if the directory cannot be opened for reading or if
.BR malloc (3)
cannot allocate enough memory to hold all the data structures.
.SH SEE ALSO
.BR directory (3),
.BR malloc (3),
.BR qsort (3),
.BR dir (5)
.SH HISTORY
The
.BR scandir 
and
.BR alphasort 
functions appeared in 4.2BSD.