Question

I have a PHP variable, say

$myvariable = "te    xt!@ na#@)(me+=&t^*ext?>;.'na^%me";

I want to replace special characters and group of special characters including blank space with a single underscore _. The string may contain & and it may be replaced with and.

The result of previous variable should be;

te_xt_na_me_andt_ext_na_me

How can I do this in PHP?

Answer 1

This assumes, anything but “characters” is regarded disposable.

$patterns = array(
    '/&/'             => 'and',  // Ampersand to "and"
    '/[^[:alpha:]]+/' => '_'     // Anything *but* a character to underscore
);

$result = preg_replace(array_keys($patterns), array_values($patterns), $input);

The last pattern replaces groups of one or more occurences of “non-word” characters according to the current locale¹ (and thus including white-space).

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¹ Side-note (might be irrelevant): if the server the script runs on has en_US as locale, the following replacements occur:

$input = 'app!le___s &!   orän=%ges';
$result = 'app_le_s_and_or_n_ges';

If the locale is de_DE, this would be the result:

$result = 'app_le_s_and_orän_ges';

Because ä is part of [[:alpha:]] in this particular locale. The obvious solution to circumvent this would be to substitute the character class for [a-zA-Z].