Python-like .format() in php

Question

I have the following array:

$matches[0] = "123";
$matches[1] = "987";
$matches[2] = "121";

And the following string:

$result = "My phone number is {0} and police number is {2}";

I would like to replace the {} placeholder based on the $matches array, in case there is no match for placeholder display nothing instead.

What is the best way to achieve that, or do you know a better solution to my problem?

(Right now I am building the system, so instead of curly brackets I could use any other symbol)

UPDATE

In python this is possible using .format() function.

Answer 1

You can do it with vsprintf, you don't have to change the order of items if you give the number (from 1) of your item like this: %n$s (where n is the number):

$matches = [ "123", "987", "121"];
$result = 'My phone number is %1$s and police number is %3$s';

$res = vsprintf($result, $matches);

Note that you have to put the formatted string between single quotes, otherwise $s will be interpreted as a variable and replaced with nothing.

(vprintf and vsprintf are designed for arrays, but you can do the same thing with printf and sprintf for separated variables, it works the same)

---

If you can't change your original Python formatted string, the way is to use preg_replace_callback:

$matches = [ "123", "987", "121"];
$result = 'My phone number is {0} and police number is {2}';

$res = preg_replace_callback('~{(\d+)}~', function ($m) use ($matches) {
    return isset($matches[$m[1]]) ? $matches[$m[1]] : $m[0];
}, $result);

or you can build an associative array where the keys are placeholders and values your array values, and use strtr for the replacement:

$matches = [ "123", "987", "121"];
$result = 'My phone number is {0} and police number is {2}';

$trans = array_combine(
    array_map(function ($i) { return '{'.$i.'}'; }, array_keys($matches)),
    $matches
);

$result = strtr($result, $trans);