Split a string, excluding some characters

Question

Possible Duplicate:
Split string by delimiter, but not if it is escaped

I have a string generated form ibm informix database which is separated by pipe | characters and there are some data errors, which means there are backslash + pipe inside the data. I want to split these strings only from the pipe sign, not from backslash + pipe \| or other signs with the pipe.

This is my code, but it works only for the pipe character:

foreach(glob("ssbstat.unl") as $file)
{ 
    $c=0;       
    if(($load = fopen($file, "r")) !== false)
    { 
        $line = fgets($load);           
        $count= count(explode('|', $line));
        echo $fm= str_repeat('%[^|]|', $count)."%s\n";      

        do
        {
            echo $line;
            print_r($line);
            if($c++>10) break;
        } while ($line = fscanf($load, $fm));
    }
}

Can anyone help me do this?

Which "other characters" did you need to exclude, what do you mean "or other signs with the pipe"? Was `\|` the *only* thing you want to ignore? — Wesley Murch, Dec 22 '11 at 13:38

noob · Answer 1 · 2011-12-22T14:22:04.510

3

Do it like this:

<?php
$line = preg_replace("/([^\\\])\|/", "$1 |", "Hi \|error\| man|ok man|perfect man");
print_r(preg_split('/[^\\\]\|/', $line));

Will output:

Array ( [0] => "Hi \|error\| man" [1] => "ok man" [2] => "perfect man" )

Testet!

Edit: Like Maerlyn said, this is also possible:

<?php
$line = "Hi \|error\| man|ok man|perfect man";
print_r(preg_split('~\\\\.(*SKIP)(*FAIL)|\|~s', $line));

edited Dec 22 '11 at 14:22

answered Dec 22 '11 at 13:52

noob

8,982
4
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65

Michael Mior · Accepted Answer · 2011-12-22T14:13:50.353

1

You can do this with preg_split. This piece [^\\\\] specifies that pipes with backslashes should be ignored (the four backslashes are required for proper escaping. You can add any other character you want to ignore inside the [].

print_r(preg_split('/(?<![\\\\])\|/', 'This\|is a|test|string'));

edited Dec 22 '11 at 14:13

answered Dec 22 '11 at 13:55

Michael Mior

28,107
9
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This won't work! a string like `'This\|is a|test|string'` will return this: `Array ( [0] => "This\|is " [1] => "tes" [2] => "string" )` because you say any char before `|` which isn't a backslash will be a part of the split function too, so it is away. That's why you should use preg_replace in before (like I have answerd) – noob Dec 22 '11 at 13:57
Good catch. I really should have been using a negative lookbehind. `preg_replace` isn't necessary. Answer updated. – Michael Mior Dec 22 '11 at 14:13

score -1 · Answer 3 · answered Dec 22 '11 at 13:34

-1

Replace backslah + pipesign with a placeholder, then explode by pipesign, then replace back placeholder with backslah + pipesign

answered Dec 22 '11 at 13:34

Massimiliano Arione

2,422
19
40

What kind of placeholder do you suggest? It would have to be something that couldn't possibly appear in the data or your last replacement may corrupt it. – Wesley Murch Dec 22 '11 at 13:37
anything that is unlikely present in your string. Something like "{[%my_great_placeholder%]}" or so – Massimiliano Arione Dec 22 '11 at 13:39
i have done it but there are about 100000 lines. it is taking hell of a time to so this. i want a short method. can this regular expression be developed??? – lankitha Dec 22 '11 at 13:39
@MassimilianoArione: It would *probably* work, but the "probably" is what keeps it from being a good idea; one that you would actually feel safe using. Unless you can be 100% sure what the data contains (or does not contain), there's no possible placeholder that you could use safely. Regular expressions are the solution for this kind of thing. – Wesley Murch Dec 22 '11 at 13:41
regexp is not faster than simple str_replace, indeed it's slower. – Massimiliano Arione Dec 22 '11 at 13:42
if there is a way to edit this regular expression. it can be done. only to select pipe sign. not other signs with pipe – lankitha Dec 22 '11 at 13:43
@lankitha: What does "other signs with pipe" mean? Each character is of course going to be next to another one, whether it's a space, newline, tan, backslash, etc. You need to be more explicit, maybe show some sample data. – Wesley Murch Dec 22 '11 at 13:44
@Madmartigan probability is just a matter of betting. I can bet whatever you want that your text is not containing the string "{[%#my_super_great_flicking_placeholder#%]}" – Massimiliano Arione Dec 22 '11 at 13:45
But guess what, now this page contains that very text. If I were running your idea on this page (of course, without *kowing* what the page contained) it would fail. Gambling is for fools! :) – Wesley Murch Dec 22 '11 at 13:47
I think you're completely missing my point... but I'll retire my argument. – Wesley Murch Dec 22 '11 at 13:51
No, I see it. But I just think you can afford a good probability just with a good choice of text. Ehi, you can also change it to something dynamic, maybe including the current date in it, or even a sha1. – Massimiliano Arione Dec 22 '11 at 14:04

Split a string, excluding some characters

3 Answers3