[RESOLVED] preg_replace problem!

[cosbeta]

I want to replace "==m(0)==","==m(1)=="..."==m(n)=="....
with the corresponding array $myarray[0] $myarray[1] ... $myarray[n]

in a string,

how can I write php regular expression replacement?

eg: $content = preg_replace("reg exp",$myarray,$content);

thank you!

[bradgrafelman]

Try this:

$content = preg_replace('/==m\(([0-9]+)\)==/e', '$myarray[$1]', $content);

[cosbeta]

thank you,but it seems does not work!😕

bradgrafelman wrote:

Try this:

$content = preg_replace('/==m\(([0-9]+)\)==/e', '$myarray[$1]', $content);

[bradgrafelman]

Worked fine for me... can we see some sample code you're trying this in?

[Installer]

I'll play the devil's advocate...

Why not simply use str_replace()?

[bradgrafelman]

How would str_replace() detect the number inside the parenthesis and use the correct array index?

[Installer]

foreach ($myarray as $key => $val) {
    $content = str_replace('==m(' . $key . ')==', $val, $content);
}

[bradgrafelman]

The way I understood it, he wanted to go the other way around:

$myarray[1] = 'hello';
$myarray[2] = 'world';

$mystring = 'Well, ==m(1)== ==m(2)==!';

$mystring = preg_replace('/==m\(([0-9]+)\)==/e', '$myarray[$1]', $mystring); 

echo $mystring; // Well, hello world!

[Installer]

bradgrafelman wrote:

The way I understood it, he wanted to go the other way around:

I'm afraid I'm at a loss as to what you mean; your code and mine produce the exact same results.

At any rate, and just for curiosity's sake, here's a speed comparison script:

$str = '';
for ($i = 0; $i < 100; $i++) {
    $myarray[$i] = '**M(' . $i . ')**';
    $str .= '/==m(' . $i . ')==/';
}

$start = microtime(true);
for ($n = 0; $n < 1000; $n++) {
    $content = $str;
    $content = preg_replace('/==m\(([0-9]+)\)==/e', '$myarray[$1]', $content);
}
echo 'preg_replace() - ' . (microtime(true) - $start) . '<br />'; 

$start = microtime(true);
for ($n = 0; $n < 1000; $n++) {
    $content = $str;
    foreach ($myarray as $key => $val) {
        $content = str_replace('==m(' . $key . ')==', $val, $content);
    }
}
echo 'str_replace() - ' . (microtime(true) - $start) . '<br />';

preg_replace() - 3.5291819572449
str_replace() - 2.9098439216614

[bradgrafelman]

D'oh! I didn't read your code snippet closely enough. I'd be interested to see if your code continues to be more efficient with more array indeces and longer strings, but either way, I'd never thought of your method.

[cosbeta]

It works,sorry for my own problem,
thank you very much.

bradgrafelman wrote:

How would str_replace() detect the number inside the parenthesis and use the correct array index?

[bradgrafelman]

Regardless of which method you chose, don't forget to mark this thread resolved (if it is).