> For the complete documentation index, see [llms.txt](https://trizen.gitbook.io/perl6-rosettacode/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://trizen.gitbook.io/perl6-rosettacode/programming_tasks/s/selectively_replace_multiple_instances_of_a_character_within_a_string.md).

# Selectively replace multiple instances of a character within a string

Set up to not particularly rely on absolute structure of the word. Demonstrate with both the original 'abracadabra' and with a random shuffled instance.

```perl
sub mangle ($str is copy) {
    $str.match(:ex, 'a')».from.map: { $str.substr-rw($_, 1) = 'ABaCD'.comb[$++] };
    $str.=subst('b', 'E');
    $str.substr-rw($_, 1) = 'F' given $str.match(:ex, 'r')».from[1];
    $str
}

say $_, ' -> ', .&mangle given 'abracadabra';

say $_, ' -> ', .&mangle given 'abracadabra'.comb.pick(*).join;
```

#### Output:

```
abracadabra -> AErBcadCbFD
caarabadrab -> cABraECdFDb
```