如何确保始终使用 PHP 对浮点数进行四舍五入？
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How can I make sure a float will always be rounded up with PHP?
提问by Sotiris
I want to make sure a float in PHP is rounded up if anydecimal is present, without worrying about mathematical rounding rules. This function would work as follows:
如果存在任何小数，我想确保 PHP 中的浮点数被四舍五入，而不必担心数学四舍五入规则。此功能将按如下方式工作：
1.1 to 2
1.2 to 2
1.9 to 2
2.3 to 3
2.8 to 3
I know the round()function exists but I don't see any function for rounding up if any decimal is found. Is there any easy way to do this?
我知道该round()函数存在，但如果找到任何小数，我看不到任何四舍五入的函数。有什么简单的方法可以做到这一点吗？
回答by ash
I know this is an old topic, however it appears in Google. I will extend Blake Plumb's answer regarding precision.
我知道这是一个古老的话题，但它出现在 Google 中。我将扩展 Blake Plumb 关于精度的回答。
ceil(1024.321 * 100) / 100;
Multiplying by 100 and dividing by 100 only works with one-hundredths. This isn't accurate on tenths, one-thousandths, one-hundred thousandths, etc.
乘以 100 并除以 100 仅适用于百分之一。这在十分之一、千分之一、千分之一等上是不准确的。
function round_up($number, $precision = 2)
{
$fig = pow(10, $precision);
return (ceil($number * $fig) / $fig);
}
Results:
结果：
var_dump(round_up(1024.654321, 0)); // Output: float(1025)
var_dump(round_up(1024.654321, 1)); // Output: float(1024.7)
var_dump(round_up(1024.654321, 2)); // Output: float(1024.66)
var_dump(round_up(1024.654321, 3)); // Output: float(1024.655)
var_dump(round_up(1024.654321, 4)); // Output: float(1024.6544)
var_dump(round_up(1024.654321, 5)); // Output: float(1024.65433)
var_dump(round_up(1024.654321, 6)); // Output: float(1024.654321)
Notes:
笔记：
Thanks for the contributions from Joseph McDermott and brandom for improving my original snippet.
感谢 Joseph McDermott 和brandom 为改进我的原始片段所做的贡献。
回答by lethalMango
回答by Blake Plumb
I know this question has long since been answered, but it came up when I did a google search on the topic. If you want to round up with precision, then a good method would be to use the ceil function and times the number by how many decimal points you want to represent and then divide by that number.
我知道这个问题早就有人回答了，但是当我对这个话题进行谷歌搜索时它出现了。如果您想精确四舍五入，那么一个好方法是使用 ceil 函数并将数字乘以要表示的小数点数，然后除以该数字。
ceil(1024.321*100)/100
would produce 1024.33
将产生 1024.33
回答by Joseph McDermott
I like Ash's response, although I would have:
我喜欢 Ash 的回答，尽管我会：
$fig = (int) str_pad('1', $precision + 1, '0');
Makes sense that if I provide precision '2', I would expect it rounded to 2 decimal places. Matter of choice though I suppose. Thanks for the answer Ash, works well.
如果我提供精度“2”，我希望它四舍五入到小数点后两位，这是有道理的。虽然我想是选择问题。感谢您的回答 Ash，效果很好。
