Php put a space in front of capitals in a string (Regex)

Question

I have a number of strings which contain words which are bunched together and I need to seperate them up. For example ThisWasCool - This Was Cool MyHomeIsHere - My Home Is Here Im slowly getting my head around regular expressions and I believe to do this I should use preg_replace. My problem is putting together the expression to find the match. I have only got this far ``` preg_replace('~^[A-Z]~', " ", $string) ``` Each string contains a lot of words, but ONLY the first word contains bunched words so using my example above a string would be "ThisWasCool to visit you again" - "This Was Cool to visit you again" I have told it to start at the beginning, and look for capitals, but what I dont know how to do is - restrict it only to the first word of each string - how to reuse the capital letter in the replace part after the space

Accepted Answer

Problem

Your regex `'~^[A-Z]~'` will match only the first capital letter. Check out Meta Characters in the Pattern Syntax for more information.

Your replacement is a newline character `'
'` and not a space.

Solution

Use this code:

```
$String = 'ThisWasCool';
$Words = preg_replace('/(?<!\ )[A-Z]/', ' $0', $String);
```

The `(?<!\ )` is an assertion that will make sure we don't add a space before a capital letter that already has a space before it.