/** 1.number_format */
$number = 1234.5678;
$nombre_format_francais = number_format($number, 2, ',', ' '); // 1234,57
$english_format_number = number_format($number, 2, '.', '');   // 1234.57(我一般用这个)

/** 2.round */
$number = 1234.5678;
echo round($number ,2); //1234.57

/** 3.sprintf */
$formatted = sprintf ("%s有¥%01.2f。", $name, $money);
echo $formatted; //张三有¥123.10。