Find the common initial substring (prefix if you insist)

Given a list of strings as the arguments, returns the initial substring (aka prefix) common to all of them.

With a trivial modification (use -$i instead of 0, $i in all of the substr calls), this could also be used to find the common terminal substring (suffix).

sub cis {
    my $first = shift;
    my $i = length $first;
    for (@_) { 
        if ((substr $_, 0, $i) eq (substr $first, 0, $i))
             {next}
        else {$i--; redo}
    }
    substr $first, 0, $i;
}
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Comment on Find the common initial substring (prefix if you insist) Download Code

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Re: Find the common initial substring (prefix if you insist) by stefp (Vicar) on Sep 20, 2001 at 02:39 UTC
For regexps abusers, with the added condition of no null character in parameter strings: `sub cis { (join( "\0", @_) =~ m/^([^\0])[^\0](\0\1[^\0])$/)[0] }` Thanks to ChemBoy for pointing an omission and compacting into one statement. -- stefp	[reply] [d/l]