input : string (sentence) output: truncated string at period, question mark or exclamation point 
# input : string (sentence)
# output: truncated string at period, question mark or exclamation poi
+nt
sub strim {
    my ($s, $i) = @_;
    $s =~ s/^\s+$//g;
    return $s unless defined $i;
    if (length $s <= $i) {
      return $s;
    } else {
        while (right(left($s, $i), 2) ne '. ' &&
               right(left($s, $i), 2) ne '? ' &&
               right(left($s, $i), 2) ne '! ') {
            $i--;
            return left($s, $_[1]) if ($i < 1);
        }
        return left($s, $i);
    }
}

# input : string, integer
# output: truncated string
sub left {
    my ($s, $i) = @_;
    return unless defined $s;
    return $s unless defined $i;
    return substr($s, 0, $i);
}

# input : string, integer
# output: truncated string
sub right {
    my ($s, $i) = @_;
    return unless defined $s;
    return $s unless defined $i;
    return substr($s, length($s) - $i, $i);
}

[download]

Replies are listed 'Best First'.
Re: Truncate a string (news lead?)
by premchai21 (Curate) on Sep 12, 2001 at 06:37 UTC 
    sub foo{($_[0]=~/^(.+[!?.]\s)/s)?$1:$_[0]}

    [download]
    Update: Fixed (twice) according to merlyn's correction(s).
[reply]
[d/l]
[reply]
[d/l]
        except my example truncates @ any number of starting characters, not just the first sentence.
[reply]
      ($_[0]=~/^(.+[!?.]\s)/s)&&$1||$_[0]

      [download]
      Do not use XX && YY || ZZ when you mean XX ? YY : ZZ, or the day your YY returns false, you will be kicking yourself.

      I don't know where this idiom started, but please do not propagate it.

      -- Randal L. Schwartz, Perl hacker

[reply]
[d/l]
[select]

        /me kicks himself.

        You're right, though for a different reason. It seems to me that, in this particular case, YY ($1) cannot be false, as it contains at least one character, then one of !?., then a whitespace character. Which cannot be false. Or, if the match fails, it contains nothing and therefore is false as it is supposed to be. Usually.

        However, it might contain the $1 from a previous match, which makes you right. Again.

[reply]

Back to Cool Uses for Perl