Replace the leading space with   with same number of times using PHP regex

Question

Hi,

I want to replace leading space with   same number of occurrences i.e.

Bit explanatory :

If one leading space exist in input then it should replace with one  

If two leading spaces exist in input then it should replace with two  

If n leading spaces are exist in input then it should replace with exact n number of times with  

Ex.1:
 My name is XYZ
output:
 My name is XYZ

Ex.2 :
  My name is XYZ
output:
  My name is XYZ

I want to replace only leading spaces, using PHP regex.

Your suggestion are welcome.

Thanks

Answer 1

$len_before = strlen($str);
$str = ltrim($str, ' ');
$len_after = strlen($str);
$str = str_repeat(' ', $len_before - $len_after) . $str;

---

Using preg_replace there is also

$str = preg_replace('/^( +)/e', 'str_repeat(" ", strlen("$1"))', $str);

but note that it uses the /e flag.

See http://www.ideone.com/VWNKZ for the result.

Answer 2

Use:

preg_replace('/^ +/m',' ',$str);

You can test it here

Answer 3

preg_replace('/\G /', ' ', $str);

\G matches the position where the last match ended, or the beginning of the string if there's no previous match.

edit: Actually, in PHP it matches where the next match is supposed to begin. That isn't necessarily the same as where the previous match ended.

Answer 4

Use preg_match with PREG_OFFSET_CAPTURE flag set, the offset is the length of the "spaces". Then use str_repeat with the offset.