If you want the first 200 characters stopping stopping at whitespace, something like this should do the job...

($text) = $var =~ /^(.{200})(?:\s+\w*)?/s;
print $text.$/;
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This saves what is captured in the first set of parentheses into $text, and the match is the first 200 characters until it hits some whitespace followed by what looks like a word. I'm sure you could probably use some of perl's extended regexp capabilities, but that seems to do the job.
HTH

broquaint

Update: apparently you can ;o)