替换字符串中的值

Question

I have a string which contains certain number of #{number} structures. For example:

#328_#918_#1358
SKU:#666:#456
TEST--#888/#982

For each #{number} structure, I have to replace it with a known string.

For the first example:
#328_#918_#1358
I have the following strings:

328="foo"
918="bar"
1358"arg"

And the result should be:
foo_bar_arg

How do I achieve such effect? My current code looks like that:

$matches = array();
$replacements = array();
// starting string
$string = "#328_#918:#1358";
// getting all the numbers from the string
preg_match_all("/\#[0-9]+/", $string, $matches);
// getting rid of #
foreach ($matches[0] as $key => &$feature) {
    $feature = preg_replace("/#/", "", $feature);
} // end foreach
// obtaining the replacement values
foreach ($matches[0] as $key => $value) {
    $replacement[$value] = "fizz"; // here the value required for replacement is obtained
} // end foreach

But I have no idea how to actually perform a replacement in $string variable using values from $replacement table. Any help is much appreciated!

Answer 1

You can use a preg_replace_callback solution:

$string = '#328_#918:#1358
SKU:#666:#456
TEST--#888/#982';
$replacements = [328=>"foo", 918=>"bar", 1358=>"arg"];
echo preg_replace_callback("/#([0-9]+)/", function ($m) use ($replacements) {
    return isset($replacements[$m[1]]) ? $replacements[$m[1]] : $m[0];
}
,$string);

See the PHP demo .

The #([0-9]+) regex will match all non-overlapping occurrences of # and one or more digits right after capturing them into Group 1. If there is an item in the replacements associative array with the numeric key, the whole match is replaced with the corresponding value. Else, the match is returned so that no replacement could occur and the match does not get removed.