Regex to change the number of spaces in an indent level

Question

Let\'s say you have some lines that look like this

1  int some_function() {
2    int x = 3;  // Some silly comment

And so on. The indentation i

Answer 1

I needed to halve the amount of spaces on indentation. That is, if indentation was 4 spaces, I needed to change it to 2 spaces. I couldn't come up with a regex. But, thankfully, someone else did:

//search for
^( +)\1 
//replace with (or \1, in some programs, like geany)
$1 

From source: "^( +)\1 means "any nonzero-length sequence of spaces at the start of the line, followed by the same sequence of spaces. The \1 in the pattern, and the $1 in the replacement, are both back-references to the initial sequence of spaces. Result: indentation halved."