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How can I split a [character] delimited string exc

Jasmine
Administrator

Jan 19, 2001, 2:55 PM

Post #1 of 1 (2549 views)

How can I split a [character] delimited string exc	Can't Post

(From the Perl FAQ)

How can I split a [character] delimited string except when inside [character]? (Comma-separated files)

Take the example case of trying to split a string that is comma-separated into its different fields. (We'll pretend you said comma-separated, not comma-delimited, which is different and almost never what you mean.) You can't use split(/,/) because you shouldn't split if the comma is inside quotes. For example, take a data line like this:

Code

    SAR001,"","Cimetrix, Inc","Bob Smith","CAM",N,8,1,0,7,"Error, Core Dumped"

Due to the restriction of the quotes, this is a fairly complex problem. Thankfully, we have Jeffrey Friedl, author of a highly recommended book on regular expressions, to handle these for us. He suggests (assuming your string is contained in $text):

Code

     @new = (); 
     push(@new, $+) while $text =~ m{ 
         "([^\"\\]*(?:\\.[^\"\\]*)*)",?  # groups the phrase inside the quotes 
       | ([^,]+),? 
       | , 
     }gx; 
     push(@new, undef) if substr($text,-1,1) eq ',';

If you want to represent quotation marks inside a quotation-mark-delimited field, escape them with backslashes (eg, "like \"this\"". Unescaping them is a task addressed earlier in this section.

Alternatively, the Text::ParseWords module (part of the standard perl distribution) lets you say:

Code

    use Text::ParseWords; 
    @new = quotewords(",", 0, $text);

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