PHP preg_replace between string and quotes

Question

I have a config file with the following content in it;

[settings]
; absolute path to the temp dir. If empty the default system tmp directory will be used
temp_path = ""

; if set to true: detects if the contents are UTF-8 encoded and if not encodes them
; if set to false do nothing
encode_to_UTF8 = "false"

; default document language
language = "en-US"

; default paper size
paper_size = "A4"

[license]
; license code
code = "8cf34efe0b57013668df0dbcdf8c82a9"

I need to replace the key between the code = "*" to something else, how can I do this with preg_replace()? The config file contains more options so I only need to replace the key between

code = "*replace me*"

It should be something like this;

$licenseKey = 'newLicenseKey';
$configFileContent = file_get_contents(configFile.ini);
$configFileContent = preg_replace('/(code = ")(.*)(")/', $licenseKey, $configFileContent);

But this replaces the whole line with only the new licenseKey.

How can i do this?

that, to me, looks like an ini file. PHP has a parse_ini_file function, that returns an array. Use that, edit what needs editing and use that data (to write a new ini file, or whatever) — Elias Van Ootegem
– Elias Van Ootegem, Commented Oct 20, 2015 at 12:37

klaar · Accepted Answer · 2015-10-20 12:52:28Z

7

You need something called PCRE Lookaround Assertions, more specifically: positive lookahead (?=suffix) and lookbehind (?<=prefix). This means you can match prefixes and suffixes without capturing them, so they will not be lost during a regex match&replace.

Your code, using those:

$licenseKey = 'newLicenseKey';
$configFileContent = file_get_contents(configFile.ini);
$configFileContent = preg_replace('/(?<=code = ")(.*)(?=")/', $licenseKey, $configFileContent);

edited Oct 20, 2015 at 12:52

answered Oct 20, 2015 at 12:32

klaar

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2 Comments

Wobbles Over a year ago

I would probably add some excludes to the check to make sure the script isn't vulnerable to attack. Should exclude " and linebreaks at the least.

Elias Van Ootegem Over a year ago

nit-pick: PREG assertions is a odd term: PREG is the prefix for all PCRE (Perl Compatible Regular Expression) functions. What you're referring to is lookaround assertions

Elias Van Ootegem · Accepted Answer · 2015-10-20 12:45:29Z

1

Like I said in my comment, I'd tackle this issue by treating the file as what it is an INI file.

Parse the file
Update values that need to change
overwrite the file or do something else (depending on your needs)

I'll assume you want to update the file, so in this example, I'll overwrite it:

$iniData = parse_ini_file('configFile.ini', true);//quote the filename
foreach ($iniData as $section => $params) {
    if (isset($params['code'])) {
        $params['code'] = $newCode;
        $iniData[$section] = $params;//update section
    }
}
//write to new file
$lines = [];//array of lines
foreach ($iniData as $section => $params) {
    $lines[] = sprintf('[%s]', $section);
    foreach ($params as $k => $v) {
        $lines[] = sprintf('%s = "%s");
    }
}
file_put_contents('configFile.ini', implode(PHP_EOL, $lines));

You can combine both loops quite easily, to simplify the code:

$lines = [];
foreach ($iniData as $section => $params) {
    if (isset($params['code'])) {
        $params['code'] = $newCode;
    }
    $lines[] = sprintf('[%s]', $section);
    foreach ($params as $k => $v) {
        $lines[] = sprintf('%s = "%s");
    }
}

answered Oct 20, 2015 at 12:45

Elias Van Ootegem

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3 Comments

klaar Over a year ago

While my answer is the answer to what the OP wants, this is the answer to what the OP needs. Therefore: +1.

Lumix1991 Over a year ago

Thanks, this is even a better solution!.

Elias Van Ootegem Over a year ago

@Lumix1991: Happy to help. Please, consider accepting an answer, depending on which answer best answered your question/was most useful or provides the best information for future reference (ie other people who might have the same question)

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