Use numeric literals with an array in PHP (preg_replace)

Question

I'm trying to use numeric literals with my array $test with preg_replace in PHP, there is what I got:

$test["a"] = "hey";

// Find a as $0
echo preg_replace("/[a-z]/", "Found:$0", "a")."\n";

// Can replace it by "hey"
echo preg_replace("/[a-z]/", $test['a'], "a")."\n";

// Can't replace it :/
echo preg_replace("/[a-z]/", $test["$0"], "a")."\n";

As you see, the last preg_replace function doesn't work, whereas the two others work fine... I tried a lot of times to include the $0 with various tricks, but nothing stills work... Can you help me, please?

Syscall · Accepted Answer · 2018-02-10T11:02:13.410

2

You can use preg_replace_callback() :

echo preg_replace_callback("/[a-z]/", function ($b) use ($test) {
    return $test[$b[0]];
}, "a")."\n";

With more tests :

echo preg_replace_callback("/[a-z]/", function ($b) use ($test) {
    if (isset($b[0]) && isset($test[$b[0]]))
        return $test[$b[0]];
    return "";
}, "a")."\n";

edited Feb 10 '18 at 11:02

answered Feb 10 '18 at 10:54

Syscall

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score 0 · Answer 2 · answered Feb 10 '18 at 11:04

Your current use case does not require regex, you can (and should if possible) use strtr or str_replace depending on what the requirements are:

$test["a"] = "hey";
$test["b"] = "you";

echo strtr("a b", $test); //hey you

echo str_replace(array_keys($test), array_values($test), "a b"); //hey you

Refer to When to use strtr vs str_replace? on what the differences are.

Use numeric literals with an array in PHP (preg_replace)

2 Answers2