Seems like this should be straightforward but the following code is not working:
$text = preg_replace('/test([0-9]+)/i', $array["$1"], $text);
The code is supposed to find all instances like 'test1', 'test2', 'test3', etc. in a text and replace with the values of $array[1], $array[2], $array[3], etc.
What am I doing wrong?
You need to use a callback:
$text = preg_replace_callback('/(test)([0-9]+)/i',
function($m) use($array) { return $m[1].$array[$m[2]]; },
$text);
The function takes the matches and uses the first capture group match concatenated with the array item with the second capture group match as the index. You might want an if in there to check that $array[$m[2]] exists first.
Alternatively you could use a loop:
foreach($array as $key => $val) {
$text = str_replace("test$key", "test$val", $text);
}
$m is for and what $m[1].$array[$m[2]] means?
You already have the answer. This one is only to explain better than in comments your assumption error.
$1 is not a result of first parameter, it is a placeholder used only by preg_replace itself. Your use invoke also the commands precedence.
In other words, if you try this code:
$text = 'Lorem test8 Dolor';
function test( $arg ) { echo $arg.PHP_EOL; }
$text = preg_replace('/test([0-9]+)/i', test("$1"), $text);
echo $text;
You obtain this output:
$1
Lorem Dolor
As you can see, first argument is evaluated, then the result is used by preg_replace: test() function receive literally $1 (and in the same way your array), not the 8 retrieved by preg_replace; then preg_replace replace matched substring by value returned in second argument: in above case test() returns nothing, so the replacement is nothing.
With this code:
function test() { return '[$1]'; }
$text = preg_replace('/test([0-9]+)/i', test(), $text);
The resulting string is:
Lorem [8] Dolor
because test() returns [$1] and it can be used by preg_replace to perform the replacement.
In your specific case, the replacement happen only if you have a scenario like this one:
$array["$1"] = 'Ipsum';
$text = preg_replace('/test([0-9]+)/i', $array["$1"], $text);
The final text is:
Lorem Ipsum Dolor
This is not your desired result, but — as mentioned earlier — you already have the answer...
preg_replace_callback()and pass the array viause()to it,