This task can be performed without using capture groups -- just use ucfirst()
.
This is not built to process multibyte characters.
Grab a word character then, optionally, the next character. From the fullstring match, only change the case of the first character.
Code: (Demo) (or Demo)
$strings = [
"test string",
"lado lomidze needs a solution",
"I made some research and found 'good' answers here; they really helped me."
]; // if not already all lowercase, use strtolower()
var_export(preg_replace_callback('/\w.?/', function ($m) { return ucfirst($m[0]); }, $strings));
Output:
array (
0 => 'TeSt StRiNg',
1 => 'LaDo LoMiDzE NeEdS A SoLuTiOn',
2 => 'I MaDe SoMe ReSeArCh AnD FoUnD \'GoOd\' AnSwErS HeRe; ThEy ReAlLy HeLpEd Me.',
)
For other researchers, if you (more simply) just want to convert every other character to uppercase, you could use /..?/
in your pattern, but using regex for this case would be overkill. You could more efficiently use a for()
loop and double-incrementation.
Code (Demo)
$string = "test string";
for ($i = 0, $len = strlen($string); $i < $len; $i += 2) {
$string[$i] = strtoupper($string[$i]);
}
echo $string;
// TeSt sTrInG
// ^-^-^-^-^-^-- strtoupper() was called here