CODEWITHSUNDEEP
regexperl
octopusgrabbus
octopusgrabbus

Reputation: 10695

How do I represent " in string?

I have example inputs to a program. They are

"1866TL", and "965937",".

The comma is part of what I am trying to match.

I want to match if there are alpha characters in the inputs.

I am getting the argument from @ARGV. 

$input_line = $ARGV[0];

if ($input_line =~ m/\A\"\d+\D+\d*\",/)
{
    print "Bad match\n";
}
else
{
    print "Good match\n";
}

If I substitute . for \", I get what I expect, Bad Match for the first example that contains TL, but not if I put literal quotes \" in the regular expression.

How do I represent this input properly as a regex?

Am I missing how =~ works? I am expecting the first value "1866TL", to match and for the program to print out Bad Match.

Interestingly, if I print out $input_line, figure the quotes have been stripped and search this way, I get what I expect.

$input_line = $ARGV[0];

print $input_line."\n";


if ($input_line =~ m/\A\d+[^0-9]+\d*/)
{
    print "Bad match\n";
}
else
{
    print "Good match\n";
}

So, what is happening? Are quotes stripped by Perl? Am I missing something else?

Upvotes: 1

Views: 131

Answers (3)

ikegami
ikegami

Reputation: 386386

So, what is happening? Are quotes stripped by Perl? Am I missing something else?

In Perl, the string literal "abc" (a piece of code) produces the string abc (a value). If you want to create the string "abc", you need to use '"abc"', "\"abc\"" or similar.

Something similar is happening in your shell. For example, in sh and derivatives, foo "abc" pass the string abc to program foo. If you want to pass "abc", you need to use foo '"abc"' or foo \"abc\" or similar.

Upvotes: 2

choroba
choroba

Reputation: 241998

The problem of your regex might be that \D matches too much, i.e. it can match double quotes and commas as well. To prevent that, use a more specific class:

m/\A"\d+[^0-9",]+\d*",/

as already adviced in https://stackoverflow.com/a/17552454/1030675.

Upvotes: 0

hobbs
hobbs

Reputation: 240364

Your code as written works just fine for me. Although there's actually no need to backslash the quotes.

Upvotes: 1

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