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<?php echo uppercase_letters('ac84894987984987AD', 0, 2); echo uppercase_letters('acaDdf984987Ad',0,10); function uppercase_letters($str, $start, $end){ $strlen = strlen($str); $str_uc = strtoupper(substr($str, $start, $end)); $then = substr($str, $end, $strlen); return $str_uc . $then; }

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49.56 ms | 402 KiB | 5 Q