camelCase to dash - two capitals next to each other

Question

I'm using this function to convert CamelCase to dashed string:

function camel2dashed($className) {
    return strtolower(preg_replace('/([^A-Z-])([A-Z])/', '$1-$2', $className));
}

it kinda works but theres problem when I have for ex. this string: getADog. It returns get-adog but I want get-a-dog

how should I change my code? Thanks

Have you considered if you wanted two capital letters next to each other? For example, companyHQ for company headquarters? You wouldn't want company-h-q, right? — jedmao, May 08 '12 at 23:11

score 38 · Accepted Answer · answered May 08 '12 at 23:08

38

Use a lookahead assertion:

function camel2dashed($className) {
    return strtolower(preg_replace('/([a-zA-Z])(?=[A-Z])/', '$1-', $className));
}

See it working online: ideone

answered May 08 '12 at 23:08

Mark Byers

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score 8 · Answer 2 · edited May 23 '17 at 12:10

You don't need a lookahead assertion to do this if you know that your string doesn't start with an upper-case letter, you can just insert a hyphen before every upper-case letter like this:

function camel2dashed($className) {
    return strtolower(preg_replace('/([A-Z])/', '-$1', $className));
}

This still won't handle cases like @sfjedi's "companyHQ" -> "company-hq". For that you'd have to explicitly test for permitted capitalized substrings that shouldn't be split, or specify some generic rules (e.g. don't prepend hyphen before last character).

You can find some more sophisticated alternatives in the answers to this virtual duplicate question.

score 0 · Answer 3 · answered Jun 21 '22 at 13:34

function camel2dash($name) {
   return ltrim(strtolower(preg_replace('/[A-Z]([A-Z](?![a-z]))*/', '-$0', $name)), '-');
}

Handles hopefully all edge cases:

SomeOfTheWords → some-of-the-words
getADog → get-a-dog
ADog → a-dog
aDog → a-dog
XML → xml
SimpleXMLReader → simple-xml-reader

camelCase to dash - two capitals next to each other

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