Php在字符串（正则表达式）中放置一个空格，留下第一个出现的空格

Question

how do i add space before capital letters but leaving the first occurence of capital letter

my string is "MyHomeIsHere" i want it to be "My Home Is Here"...but with the code below i get as " My Home Is Here" space gets added before M too

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

Answer 1

As an answer using @SebastianProske's expression with explanations and a demo link to ideone:

<?php

$string = 'MyHomeIsHere';
$regex = '~     # delimiters
        \B      # match where \b (a word boundary) does not match
        [A-Z]   # one of A-Z
        ~x';        # free spacing mode for this explanation

$words = preg_replace($regex, ' $0', $string);
echo $words;
# output: My Home Is Here

?>

See it working on ideone.com.