CODEWITHSUNDEEP
perlreplacesubstr
rickyduck
rickyduck

Reputation: 4084

Why can't my Perl script differentiate between `0` and `" "`?

Perl noob here - i have the following script

if(substr($pc, 3,1)!=" "){
       $newpc = substr($pc, 0, 4) . " " . substr($pc, 4);
}

It's designed to put a space in postcodes, for example NN141NJ becomes NN14 1NJ... however with postcodes such as NN102DE it doesn't do anything, does Perl recognize " " and "0" as the same? How can I go about perl not ignoring strings with 0 as the fourth letter?

Upvotes: 2

Views: 141

Answers (4)

zgpmax
zgpmax

Reputation: 2847

In Perl, this sort of string-bashing is usually done using regular expression operators.

So you might want to look at using m// and/or s///.

See "Regexp Quote-Like Operators" in the perlop documentation page, and also the whole perlretut documentation page.

Then again, if you are dealing with UK postcodes you might want to search for "Postcode" on CPAN or look at Geo::Postcode

Upvotes: 1

Cfreak
Cfreak

Reputation: 19309

It's because perl needs specification between string comparison and numeric comparison. You're using numeric comparison which would convert " " to a 0. Do this instead:

if(substr($pc, 3,1) ne " "){
       $newpc = substr($pc, 0, 4) . " " . substr($pc, 4);
}

Upvotes: 3

Jonah Bishop
Jonah Bishop

Reputation: 12581

You are using the != operator when you want to be using the ne (not-equal) operator. != is a numeric-only compare, while ne is a string compare.

Upvotes: 3

e.dan
e.dan

Reputation: 7487

Use ne instead of !=. The latter is for numeric comparisons, in which both are 0 in your case. See perldoc perlop

Upvotes: 7

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