my $long_string = 'string' x 5;
print $long_string,$/;

substr( $long_string, 6 ) = ''; # truncate to 6 characters

#
# same thing, only using 4 arg substr
# substr( $long_string, 6, length($long_string) - 6, '' );
#

print $long_string,$/;
__END__
stringstringstringstringstring
string
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4-arg substr isn't optimized for void context. It will set up the replaced string to be returned regardless.

The lvalue substr doesn't actually return the string but a special lvalue indicating the offset and length. Creating this and setting it to '' involves a fair amount of overhead.

Which is actually more efficient will probably depend on how much you are truncating.

It was originally part of a log reader. I found that reading in blocks and working pattern matching on those blocks was much more efficient than on line by line. Obviously you can get partial lines, so I rindex the last /n, save the fragment at the end for the next pass and return the main block truncated. It works like a charm. I was reinventing it and seing how I could make it more efficient.

Ty, How embarrasing, that simple eh? Thanks again, sigh. :)