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.Dd $Mdocdate: March 26 2010 $
.Dt SCANDIR 3
.Os
.Sh NAME
.Nm scandir ,
.Nm alphasort
.Nd scan a directory
.Sh SYNOPSIS
.Fd #include <sys/types.h>
.Fd #include <dirent.h>
.Ft int
.Fn scandir "const char *dirname" "struct dirent ***namelist" "int \*(lp*select\*(rp\*(lpstruct dirent *\*(rp" "int \*(lp*compar\*(rp\*(lpconst void *, const void *\*(rp"
.Ft int
.Fn alphasort "const void *d1" "const void *d2"
.Sh DESCRIPTION
The
.Fn scandir
function reads the directory
.Fa dirname
and builds an array of pointers to directory
entries using
.Xr 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
.Fa namelist .
.Pp
The
.Fa select
parameter is a pointer to a user-supplied subroutine which is called by
.Fn 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
.Fa select
is
.Dv NULL ,
then all directory entries will be included.
.Pp
The
.Fa compar
parameter is a pointer to a user-supplied subroutine which is passed to
.Xr qsort 3
to sort the completed array.
If this pointer is
.Dv NULL ,
the array is not sorted.
.Pp
The
.Fn alphasort
function is a routine which can be used for the
.Fa compar
parameter to sort the array alphabetically.
.Pp
The memory allocated for the array can be deallocated with
.Xr 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
.Xr malloc 3
cannot allocate enough memory to hold all the data structures.
.Sh SEE ALSO
.Xr directory 3 ,
.Xr malloc 3 ,
.Xr qsort 3 ,
.Xr dir 5
.Sh HISTORY
The
.Fn scandir
and
.Fn alphasort
functions appeared in
.Bx 4.2 .