Using a regex, how can I delete some colons and replace others with spaces?

Question

It is necessary regexp to replace in a line of a colon with blanks, excepting situations where a colon the first and (or) last symbol - them is simply deleted.

Example1
"6:206:НР" -> "6 206 НР"

Example2
":206:" -> "206"

Answer 1

You can't do conditional replacement with a single regex alone. You'll need to use your language's library. Python example:

s = s.replace(':', ' ').strip()

If you absolutely need to do it through regex, you can use two of them. Example:

s = re.sub(':', ' ', re.sub('^:|:$', '', s))

Answer 2

In PHP you can do:

$from = array('/^:|:$/','/:/');
$to = array('',' ');
$output = preg_replace($from,$to,$input);

Answer 3

It's hardly necessary to use regular expressions for such a trivial task. Replace all colons with spaces first, then trim the resulting string to get rid of spaces before and after the data.

PHP Syntax:

$string = trim(str_replace(':', ' ', $string));