PHP四舍五入 保留幾位小數 格式化數字

<?php

/* 1.number_format /
$number = 1234.56789;
$nombre_format_francais = number_format($number, 2, ',', ' ');
$english_format_number = number_format($number, 2, '.', '');
/* 2.round /
$number = 1234.56789;
echo round($number ,2);
/* 3.sprintf /
$formatted = sprintf ("￥%01.2f。", $money);
echo $formatted;
?></pre>