CODEWITHSUNDEEP
regexperl
user3064085
user3064085

Reputation: 53

Perl substitution example from Mastering Regular Expressions book not working for me

I'm probably just missing something simple but the s/// isn't assigning the changed string to my variable. I try a more simple s/// and it does work.

This example should trim the any digits after the decimal if there are more than three.

my $price = 12.34567;
print "$price\n";
$price =~ s/(\.\d\d[1-9]?)d*/$1/;
print "$1\n";           # This is printing .345 correctly.
print "$price\n";       # This should be 12.345 but is unchanged.

my $story = "dog";
$story =~ s/(do)g/$1/;
print "$story\n"; # This works.  It's changed to "do"

Edit: If the third digit is a zero it should trim it after two digits.

"Prettifying a stock Price: ...always take the first two digits after the decimal point, and take the third digit only if it is not zero. Then, remove any other digits.

Upvotes: 3

Views: 105

Answers (2)

Valdi_Bo
Valdi_Bo

Reputation: 30971

Indeed, you missed only a backslash before the last "d".

Change the first substiturion instruction to:

$price =~ s/(\.\d\d[1-9]?)\d*/$1/;

Upvotes: 0

Borodin
Borodin

Reputation: 126722

Your substitution is wrong.

$price =~ s/(\.\d\d[1-9]?)d*/$1/;

should be

$price =~ s/(\.\d\d[1-9]?)\d*/$1/;

Your own version matches because d* can match an empty string, which it does because there are no d characters after the third decimal place

It seems odd to insist that any third decimal digit must be non-zero. So 0.00 is fine, but 0.000 is not, and will be truncated to the former. Is that what you intended?

Upvotes: 1

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