Description:
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Three of four ASCII case conversion functions have equivalent modes of mb_convert_case():

1. strtoupper -> MB_CASE_UPPER
2. strtolower -> MB_CASE_LOWER
3. ucwords    -> MB_CASE_TITLE
4. ucfirst    -> ???

What's with the fourth? Would come in handy when you use some dynamic text at the beginning of a sentence.

Test script:
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/* example by info at yasarnet dot com */
function capitalize($str, $encoding = 'UTF-8') {
    return mb_strtoupper(mb_substr($str, 0, 1, $encoding), $encoding) . mb_strtolower(mb_substr($str, 1, mb_strlen($str), $encoding), $encoding);
}