I don't address efficiency here. Unless your directory is very big, your approach should be efficient enough.

Just a couple of comments on your code, though:

1) In windows, you don't need to use the backslash as a path separator thingy, you can use a forward slash, which doesn't need escaping. This means that instead of typing for example:

my $path = 'c:\\perl\\progs\\testing';

You can do:

my $path = 'c:/perl/progs/testing';

which is a lot easier to type (and easier to read).

2) Change your line:

close (DIR);

to:

closedir (DIR);

3) Re the first line inside your sub:

($path)=@_;

This is usually written something like:

my $whatever = $_[0];

or else:

my $whatever = shift;

Note that this uses a distinct variable limited to the scope of the sub, which is generally a Good Idea. Indeed, you could even do away with this line and have as the first line of your sub:

opendir (DIR, shift) || die "$!";

4) Lastly, considering this line:

my @files=grep{/\.c$/} readdir(DIR);

I would recommend that you also test that everything that you put into @files really is a file (rather than a directory, for example):

my @files = grep{ -f and /\.c$/ } readdir(DIR);

dave