Use the -M test operator. It returns the age of a file in days, so, for example, if you want to process only files from yesterday, the code could look like this: (untested)

foreach my $file (@filelist) {
    if ( int( -M $file ) < 1 ) {
        # do something with a file
    }
}
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int () is used because -M returns values like 0.50 when a file is less than a day old.

If you want to perform a specific task, please tell what you want to do with the files, I'll be glad to write some example code.

As Utilitarian was kind enough to suggest, readdir works just fine. However, I would try using File::Find, its both simple and powerful, in case you'll need some extra functionality later on. Here's an example of it's use: (this time it's tested ;] )

#!/usr/bin/perl -w
use strict;
use File::Find;

my $directory = "d:/usr";

print "List of files newer than yesterday in $directory:\n";

find(\&process, $directory);
sub process {
    if ((int(-M) < 1) && (-f)) {
        print "  $File::Find::name\n";
    }
}
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Output:

List of files newer than yesterday in d:/usr:
  d:/usr/newfile1.txt
  d:/usr/newfile2.txt
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The -f file test operator ensures we process only files, normally the output would contain d:/usr too. The process sub is executed for every file found in a directory, so feel free to modify it for your own needs.

Rgards,
Luke

opendir (DIR,"./");
@files = readdir DIR;
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foreach $file (@files){
if ( -f $file){
my ($dev,$ino,$mode,$nlink,$uid,$gid,$rdev,$size,$atime,$mtime,$ctime,
+$blksize,$blocks)= stat($file);
push (@wanted) $file if ((time() - $mtime) < (24*60*60);
}
}
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Instead of stat() and calculating the age in days yourself, that is returned by the -M operator.

my @wanted = grep -f $_ && -M _ < 1, @files;
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or something close to that.