How to replace words outside double and single quotes

Question

For a custom script parser in PHP I would like to replace some words in a multiline string that contain double and single quotes. However, only the text that is outside the quotes can be replaced.

Many apples are falling from the trees.    
"There's another apple over there!"    
'Seedling apples are an example of "extreme heterozygotes".'

For example, I would like to replace 'apple' with 'pear', but only outside the quote sentences. So in this case only 'apple' inside 'Many apples are falling from the trees' would be targeted.

The above would give the following output:

Many pears are falling from the trees.    
"There's another apple over there!"    
'Seedling apples are an example of "extreme heterozygotes".'

How can I achieve this?

Can you post your PHP Parsing script so that we can suggest the modifications. — Praveen Kumar Purushothaman, Jun 07 '12 at 09:17

Timm · Accepted Answer · 2012-06-08T13:22:44.993

5

This function does the trick:

function str_replace_outside_quotes($replace,$with,$string){
    $result = "";
    $outside = preg_split('/("[^"]*"|\'[^\']*\')/',$string,-1,PREG_SPLIT_DELIM_CAPTURE);
    while ($outside)
        $result .= str_replace($replace,$with,array_shift($outside)).array_shift($outside);
    return $result;
}

How it works It splits by quoted strings but includes these quoted strings, this gives you alternating non-quoted, quoted, non-quoted, quoted etc strings in an array (some of the non-quoted strings may be blank). It then alternates between replacing the word and not replacing, so only non-quoted strings are replaced.

With your example

$text = "Many apples are falling from the trees.    
        \"There's another apple over there!\"    
        'Seedling apples are an example of \"extreme heterozygotes\".'";
$replace = "apples";
$with = "pears";
echo str_replace_outside_quotes($replace,$with,$text);

Output

Many pears are falling from the trees.    
"There's another apple over there!"    
'Seedling apples are an example of "extreme heterozygotes".'

edited Jun 08 '12 at 13:22

answered Jun 07 '12 at 09:26

Timm

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I couldn't get the regex used in my [first answer](http://stackoverflow.com/revisions/10929115/1) to work reliably, so I created this function instead which does always work. – Timm Jun 08 '12 at 13:28
1

I tested your script and found a bug. If you have the escaped characters \' or \" in your string it will close early leading to unpredictable results. This regex fixes it /('(?:[^\\\\']+|\\\$\\\\\\\$*.)*'|\"(?:[^\\\\\"]+|\\\$\\\\\\\$*.)*\")/ . It's not pretty but it works. There must be a more elegant solution but I can't waste more time on this right now. – Dieter Gribnitz Mar 10 '15 at 09:28
As Dieter says, the sample code doesn't work for the following : `$test="x('\'y');y(1);console(\"xyz\",xyz); echo "
".$this->str_replace_outside_quotes("y", "z", $test);` BUT using Dieters version does work

user1432181

Apr 14 '21 at 16:33

score 1 · Answer 2 · answered Jun 07 '12 at 09:22

I came up with this:

function replaceOutsideDoubleQuotes($search, $replace, $string) {
    $out = '';
    $a = explode('"', $string);
    for ($i = 0; $i < count($a); $i++) {
        if ($i % 2) $out .= $a[$i] . '"';
        else $out .= str_replace($search, $replace, $a[$i]) . '"';
    }
    return substr($out, 0, -1);
}

The logic is: you explode string by double-quotes, so the odd elements of the returning string-array represent text outside quotes, and even ones represents text inside double-quotes.

So, you can build your output by concatenating original parts and replaced parts alternatively, ok?

Working example here: http://codepad.org/rsjvCE8s

Thanks but it works only for the double quotes...I would need something that only replaces outside of double AND single quotes :) — Nick, Jun 07 '12 at 09:28

score 0 · Answer 3 · answered Jun 07 '12 at 09:19

0

Just a thought: create a temporary string by removing quoted parts, replace what you need to, then add the quoted parts you removed.

answered Jun 07 '12 at 09:19

slash197

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How do you re-add the quoted parts to the original string, in their original positions? – Nick Jun 07 '12 at 09:52

score 0 · Answer 4 · answered Jun 07 '12 at 09:25

0

You can use preg_replace, using a regular expression to replace the words inside " "

$search  = array('/(?!".*)apple(?=.*")/i');
$replace = array('pear');
$string  = '"There\'s another apple over there!" Seedling apples are an example of "extreme heterozygotes".';

$string = preg_replace($search, $replace, $string);

You can add more possible searchable objects by adding another RegEx in $search, and another replace string in $replace

This RegEx uses a lookahead and lookbehind to find out if the searched string is inside of " "

answered Jun 07 '12 at 09:25

Katai

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I'm sorry, I just noticed that I read the question wrong - the opposite was asked. I'll change it... – Katai Jun 07 '12 at 09:31
It seems to do the opposite of what the question asks, replacing text **inside** the quotes, and not outside. – Alexandre R. Janini Sep 10 '17 at 21:55

How to replace words outside double and single quotes

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