Replace part of string only the first time, WITH offset

Question

I want to parse a text file, and make the timestamp (if present) colored and bold. Basically, the text could look like this:

15:40 - User1: hey
15:41 - User2: i was about to hit the road, but have at it
15:42 - User1: i was just wondering

Now, I explode on \r\n (which is already stupid because lines may contain a break itself, but leaving that aside for now), so I go through it with a foreach loop.

$string = explode("\r\n", $file);
foreach($string as $ex) {
    echo "<p>".$ex."</p>\r\n";
}

Let's say I want to bold the entire timestamp, including username. A str_replace wouldn't work, as : is also in the timestamp. My question is, how do I bold that entire part? A strpos checking for " - " leaves me with offset 5, but how to bold the entire part until the next presence of a colon? (again, leaving aside people may have a colon in their username)

Hell, if I can one up myself, any chance there's a possibility of it changing to $timestamp, $seperator, $user and $message?

Kind regards,

Wesley

Answer 1

You 'd be much better off using a regular expression here:

$bolded = preg_replace('/^\d+:\d+\s*-\s*[^:]+/', '<b>$1</b>', $ex);

This matches the pattern ^\d+:\d+\s*-\s*[^:]+ and replaces it with <b>$1</b>, which really means that the match is placed inside bold tags (use <strong> for more semanticness, this is just an example).

What does ^\d+:\d+\s*-\s*[^:]+ match?

^      at the start of the string...
\d+    one or more digits             -+
:      a double colon                  +---> the time
\d+    one or more digits             -+
\s*    zero or more whitespace
-      a dash
\s*    zero or more whitespace
[^:]+  one or more of "not :"         -----> the username

Answer 2

You can use strpos() with an offset:

foreach($array as $value) {
    $needle = ':';
    $pos1 = strpos($value, $needle);
    $pos2 = strpos($value, $needle, $pos1 + strlen($needle));
    $bold = substr($value, 0, $pos2);
    $notBold = substr($value, $pos2);
    echo "<p><strong>$bold</strong>$notBold</p>";
}

Demo!