Converting snake_case to PascalCase

Question

Is there an effective way, maybe with regex, to change the following text pattern?

I have a string like abc_def_ghi_jkl. I want to replace it to AbcDefGhiJkl. I currently use the following code to change it. Is there a more effective way than this?

implode('',array_map('ucfirst',explode('_',$string)));

• Nicolas Raoul: What you describe is usually called PascalCase.

Answer 1

More effective solution:

str_replace('_', '', ucwords($key, '_'));

From Gears library

• mdfst13: Hi. Welcome to Code Review! Why is this solution more effective?
• Cosmologist: Because, array_map is expensive operation
• starbeamrainbowlabs: Here's a test that proves the above point: repl.it/ERrZ/6 (For the lazy: array_map: 575ms, str_replace: 365ms). Suggestion: Add more of an explanation next time :-)
• tom10271: Why not str_replace('_', '', ucwords($key, '_'))? It is faster and code shorter by setting delimiter directly in ucwords
• Cosmologist: @aokaddaoc, good solution!

Answer 2

I know, its not the latest question, but here is another solution.

Not really pretty, but works well, is in one line and has a better performance than the solution in the question: str_replace(' ', '', ucwords(str_replace(['-', '_'], ' ', $str)))

BTW. here are some microtime results from my server:

// 9.0599060058594E-6
// 
$result = implode('',array_map('ucfirst',explode('_',$string)));
// 4.2915344238281E-5
// 
$result = preg_replace_callback("/(?:^|_)([a-z])/", function($matches) {
 return strtoupper($matches[1]);
}, $string);
// 5.0067901611328E-6
// 
$result = str_replace(' ', '', ucwords(str_replace(['-', '_'], ' ', $string)));

Answer 3

You could use preg_replace_callback(), which replaces matches with the result of a function:

$str = "abc_def_ghi_jkl";
$str = preg_replace_callback("/(?:^|_)([a-z])/", function($matches) {
// Start or underscore ^ ^ lowercase character
 return strtoupper($matches[1]);
}, $str);
echo $str;

Whichever works for you, your solution is fine as well.