You could get a hint from the documentation:

perldoc -f reverse

but I have this on the shelf:

#!/usr/bin/perl -w
print join(" ", reverse split /\s/), "\n" for (reverse <STDIN>);
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i am very thank ful for the help extended same thing i its working how can i reverse the content of each file?? i.e if a file contains lee jones can i have it as jones lee.

I personally believe that since this is a wholly different question, then you should start a new thread. Notice: one new thread, not a hundred like the list time. Before you do so, please pause a little, take a deep breath and review your requirements: your specs as of now are far too poor - are your files expected to only contain strings like "lee jones"? In the IMHO unlikely case that is actually so, you may be content with

print reverse split /(\s+)/;
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in conjunction with the $^I special variable. If you only want to replace the fixed string "lee jones" with "jones lee" everywere, then

s/lee jones/jones lee/g;
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may be enough. But things may become trickier if spacing is not uniform, case does matter and you want to preserve it, and so on. In any case, you have to tell us.