在php中查找具有特定字符串模式的子字符串

Question

I want to find substring in a string with ___string_string___ pattern where string_string can be any string.

$string = "This string contains ___MY_VALUE___ which I want to replace and there is also ___ONE_MORE_VALUE___ which I want to replace";`

Answer 1

The solution using preg_replace_callback with specific regex pattern:

// custom replacement list
$pairs = ['___MY_VALUE___' => 123, '___ONE_MORE_VALUE___' => 456];
$str = '"This string contains ___MY_VALUE___ which I want to replace and there is also ___ONE_MORE_VALUE___ which I want to replace";';

$str = preg_replace_callback('/___(([a-z]+_?)+)___/mi', function($m) use($pairs){
    return (isset($pairs[$m[0]]))? $pairs[$m[0]] : $m[0];
}, $str);

print_r($str);

The output:

"This string contains 123 which I want to replace and there is also 456 which I want to replace";