preg_replace删除除破折号，字母，数字，空格和下划线以外的所有字符

Question

I need to remove all characters in a string except dashes, letters, numbers, spaces, and underscores.

Various answers on SO come tantalizingly close ( Replace all characters except letters, numbers, spaces and underscores , Remove all characters except letters, spaces and apostrophes , etc.) but generally don't include dashes.

Help would be greatly appreciated.

Answer 1

You could do something like below:

    $string = ';")<br>kk23how nowbrowncow_-asdjhajsdhasdk32423ASDASD*%$@#!^ASDASDSA4sadfasd_-?!'; 
    $new_string = preg_replace('/[^ \w-]/', '', $string);
    echo $new_string;

• [^] represents a list of characters NOT to match
• \\w is a short for word character [A-Za-z0-9_]
• - matches a hyphen literally

Answer 2

You probably need something like:

$new = preg_replace('/[^ \w-]/', '', $old);

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Explanation :

[^ \w-]

Match any single character NOT present in the list below «[^ \w-]»
   The literal character “ ” « »
   A “word character” (Unicode; any letter or ideograph, any number, underscore) «\w»
   The literal character “-” «-»

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Demo