php 删除两个小数点后的数字，而不对值进行四舍五入
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Delete digits after two decimal points, without rounding the value
提问by air
i have value in php variable like that
我在 php 变量中有这样的值
$var='2.500000550';
echo $var
what i want is to delete all decimal points after 2 digits.
我想要的是删除 2 位数字后的所有小数点。
like now value of variable will be
就像现在变量的值将是
$var='2.50';
echo $var
keep in mind this value is coming from mysql databse
请记住此值来自 mysql 数据库
but when i use round php functioni got round but i dont need round, i just need to delete all digits after 2 decimal simple.
但是当我使用时，round php function我得到了圆但我不需要圆，我只需要简单地删除 2 个小数点后的所有数字。
i have tired, flot()and lot of other option no success.
我累了，flot()很多其他选择都没有成功。
Thanks
谢谢
回答by random_user_name
TL;DR:
特尔；博士：
The PHP native function bcdivseems to do precisely what is required, and properly.
PHP 本机函数bcdiv似乎完全正确地完成了所需的工作。
To simply "truncate" a number, bcdiv($var, 1, 2);where 2 is the number of decimals to preserve (and 1 is the denomenator - dividing the number by 1 allows you to simply truncate the original number to the desired decimal places)
简单地“截断”一个数字，bcdiv($var, 1, 2);其中 2 是要保留的小数位数（1 是分母 - 将数字除以 1 允许您简单地将原始数字截断到所需的小数位）
Full Answer (for history)
完整答案（历史）
This turns out to be more elusive than one might think.
事实证明，这比人们想象的更难以捉摸。
After this answer was (incorrectly) upvoted quite a bit, it has come to my attention that even sprintf will round.
在这个答案（错误地）得到了相当多的支持后，我注意到即使是 sprintf 也会四舍五入。
Rather than delete this answer, I'm turning it into a more robust explanation / discussion of each proposed solution.
我没有删除这个答案，而是将它变成对每个提议的解决方案的更可靠的解释/讨论。
number_format - Incorrect. (rounds)
Try using number format:
number_format - 不正确。（轮）
尝试使用数字格式：
$var = number_format($var, 2, '.', ''); // Last two parameters are optional
echo $var;
// Outputs 2.50
If you want it to be a number, then simply type-cast to a float:
如果你希望它是一个数字，那么只需将类型转换为浮点数：
$var = (float)number_format($var, 2, '.', '');
Note:as has been pointed out in the comments, this does in fact roundthe number.
注意：正如评论中指出的那样，这实际上是对数字进行四舍五入。
sprintf - incorrect. (sprintf also rounds)
If not rounding the number is important, then per the answer below, use sprintf:
sprintf - 不正确。（ sprintf 也
舍入）如果不舍入数字很重要，那么根据下面的答案，使用sprintf：
$var = sprintf("%01.2f", $var);
floor - not quite! (floor rounds negative numbers)
地板 - 不完全！（地板四舍五入负数）
floor, with some math, will come close to doing what you want:
floor，通过一些数学运算，将接近做你想做的事：
floor(2.56789 * 100) / 100; // 2.56
Where 100 represents the precision you want. If you wanted it to three digits, then:
其中 100 代表您想要的精度。如果你想要三位数，那么：
floor(2.56789 * 1000) / 1000; // 2.567
However, this has a problem with negative numbers. Negative numbers still get rounded, rather than truncated:
但是，这有负数的问题。负数仍然被四舍五入，而不是被截断：
floor(-2.56789 * 100) / 100; // -2.57
"Old" Correct answer: function utilizing floor
“旧” 正确答案：利用楼层的功能
So a fully robust solution requires a function:
所以一个完全健壮的解决方案需要一个函数：
function truncate_number( $number, $precision = 2) {
// Zero causes issues, and no need to truncate
if ( 0 == (int)$number ) {
return $number;
}
// Are we negative?
$negative = $number / abs($number);
// Cast the number to a positive to solve rounding
$number = abs($number);
// Calculate precision number for dividing / multiplying
$precision = pow(10, $precision);
// Run the math, re-applying the negative value to ensure returns correctly negative / positive
return floor( $number * $precision ) / $precision * $negative;
}
Results from the above function:
上述函数的结果：
echo truncate_number(2.56789, 1); // 2.5
echo truncate_number(2.56789); // 2.56
echo truncate_number(2.56789, 3); // 2.567
echo truncate_number(-2.56789, 1); // -2.5
echo truncate_number(-2.56789); // -2.56
echo truncate_number(-2.56789, 3); // -2.567
New Correct Answer
新的正确答案
Use the PHP native function bcdiv
使用 PHP 原生函数bcdiv
echo bcdiv(2.56789, 1, 1); // 2.5
echo bcdiv(2.56789, 1, 2); // 2.56
echo bcdiv(2.56789, 1, 3); // 2.567
echo bcdiv(-2.56789, 1, 1); // -2.5
echo bcdiv(-2.56789, 1, 2); // -2.56
echo bcdiv(-2.56789, 1, 3); // -2.567
回答by Sujit Agarwal
floor(2.500000550 * 100) / 100;
This should do your task...
这应该可以完成你的任务......
回答by flu
You're requesting a function that returns "2.50"and not 2.5, so you aren't talking about arithmetichere but string manipulation. Then preg_replaceis your friend:
您正在请求一个返回"2.50"而不是返回的函数2.5，因此您在这里谈论的不是算术而是字符串操作。然后preg_replace是你的朋友：
$truncatedVar = preg_replace('/\.(\d{2}).*/', '.', $var);
// "2.500000050" -> "2.50", "2.509" -> "2.50", "-2.509" -> "2.50", "2.5" -> "2.5"
If you want to do it with arithmetic, simply use:
如果你想用算术来做，只需使用：
$truncatedVar = round($var * 100) / 100);
// "2.500000050" -> "2.5", "2.599" -> "2.59", "-2.599" -> "2.59"
回答by matino
回答by Liphtier
number_format rounds the number
number_format 舍入数字
php > echo number_format(128.20512820513, 2)."\n";
128.21
I used preg_replace to really cut the string
我用 preg_replace 来真正切断字符串
php > echo preg_replace('/(\.\d\d).*/', '', 128.20512820513)."\n";
128.20
回答by David Constantine
someone posted here about
有人在这里发布了关于
floor(2.500000550 * 100) / 100;
楼层(2.500000550 * 100) / 100;
function cutAfterDot($number, $afterDot = 2){
$a = $number * pow(10, $afterDot);
$b = floor($a);
$c = pow(10, $afterDot);
echo "a $a, b $b, c $c<br/>";
return $b/$c ;
}
echo cutAfterDot(2.05,2);
a 205, b 204, c 100
2.04
so in raw form don't use it... But if you add a little epsilon...
所以在原始形式中不要使用它......但是如果你添加一点epsilon......
function cutAfterDot($number, $afterDot = 2){
return floor($number * pow(10, $afterDot) + 0.00001) / pow(10, $afterDot);
}
it works!
有用！
回答by Faisal
Use the PHP native function bcdiv.
使用 PHP 原生函数bcdiv。
Example:
例子：
echo bcdiv(3.22871, 1, 1); // 3.2
echo bcdiv(3.22871, 1, 2); // 3.22
echo bcdiv(3.22871, 1, 3); // 3.228
echo bcdiv(-3.22871, 1, 1); // -3.2
echo bcdiv(-3.22871, 1, 2); // -3.22
For your case:
对于您的情况：
$var='2.500000550';
echo $var
echo bcdiv($var, 1, 2); // 2.50
回答by Sujjad A
$num = 118.74999669307;
$cut = substr($num, 0, ((strpos($num, '.')+1)+2));
// Cut the string from first character to a length of 2 past the decimal.
// substr(cut what, start, ( (find position of decimal)+decimal itself)+spaces after decimal) )
echo $cut;
回答by Jon C.
floor - not quite! (floor rounds negative numbers)
地板 - 不完全！（地板四舍五入负数）
A possible solution from cale_banswer.
来自cal_b答案的可能解决方案。
static public function rateFloor($rate, $decimals)
{
$div = "1" . str_repeat("0", $decimals);
if ($rate > 0) {
return floor($rate * $div) / $div;
}
$return = floor(abs($rate) * $div) / $div;
return -($return);
}
static public function rateCeil($rate, $decimals)
{
$div = "1" . str_repeat("0", $decimals);
if ($rate > 0) {
return ceil($rate * $div) / $div;
}
$return = ceil(abs($rate) * $div) / $div;
return -($return);
}
Positive
积极的
Rate: 0.00302471
Floor: 0.00302400
Ceil: 0.00302500
比率：0.00302471
楼层：0.00302400
天花板：0.00302500
Negative
消极的
Rate: -0.00302471
Floor: -0.00302400
Ceil: -0.00302500
比率：-0.00302471
楼层：-0.00302400
上限：-0.00302500
