Perl - skip the classics and use regular expressions

Archive - Originally posted on "The Horse's Mouth" - 2010-06-08 20:45:38 - Graham Ellis

Perl includes a number of "classic" string handling functions - things like index to find one string in another and substr to get a substring. But you very rarely need to use them because the other string handling functions that are provided are so much more powerful!

Here's an example - firstly showing the Perl way to replace one string with another, then the "classic" method that might be used by someone who's familiar with C and perhaps hasn't been on our Perl Course.

print "Where are you? ";

chop($place = <STDIN>);

 

$showem = "It is nice to be in HERE in June\n";

$showem =~ s/HERE/$place/;

print $showem;

 

$showem = "It is nice to be in HERE in June\n";

$pol = index($showem,"HERE");

$part1 = substr($showem,0,$pol);

$part2 = substr($showem,$pol+4);

$showem = $part1 . $place . $part2;

print $showem;

So that's 4 lines replaced by one and they have exactly the same effect:

Dorothy-2:de grahamellis$ perl altern

Where are you? Nuremberg

It is nice to be in Nuremberg in June

It is nice to be in Nuremberg in June

Dorothy-2:de grahamellis$

Oh - I tested the data using "Nuremberg" as my input, as that's where I am training this week. And it is nice in Nuremberg, although I would love to have had someone here to share it with me ;-).

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Perl - skip the classics and use regular expressions