ScotlandPHP

bcscale

(PHP 4, PHP 5, PHP 7)

bcscale设置所有bc数学函数的默认小数点保留位数

说明

bool bcscale ( int $scale )

设置所有bc数学函数的未设定情况下得小数点保留位数.

参数

scale

小数点保留位数.

返回值

成功时返回 TRUE, 或者在失败时返回 FALSE

范例

Example #1 bcscale() example

<?php

// default scale : 3
bcscale(3);
echo 
bcdiv('105''6.55957'); // 16.007

// this is the same without bcscale()
echo bcdiv('105''6.55957'3); // 16.007

?>

add a note add a note

User Contributed Notes 7 notes

up
13
mwgamera at gmail dot com
9 years ago
These functions DO NOT round off your values. No arbitrary precision libraries do it this way. It stops calculating after reaching scale of decimal places, which mean that your value is cut off after scale number of digits, not rounded. To do the rounding use something like this:
<?php
       
function bcround($number, $scale=0) {
               
$fix = "5";
                for (
$i=0;$i<$scale;$i++) $fix="0$fix";
               
$number = bcadd($number, "0.$fix", $scale+1);
                return   
bcdiv($number, "1.0",    $scale);
        }
?>
up
1
sicerwork at aliyun dot com
9 months ago
Executing bcsacle() will change the scale value of fpm.conf, not only the current process.
up
0
herslyadam at gmail dot com
3 years ago
edited bcround function with negative number support:
<?php
function bcround($number, $scale=0) {
    if(
$scale < 0) $scale = 0;
   
$sign = '';
    if(
bccomp('0', $number, 64) == 1) $sign = '-';
   
$increment = $sign . '0.' . str_repeat('0', $scale) . '5';
   
$number = bcadd($number, $increment, $scale+1);
    return
bcadd($number, '0', $scale);
}
?>
up
-2
invincible at limitedintelligence dot com
11 years ago
If you don't set the default scale, be careful when you're chaining together several BC math functions - since by default, these functions will round off your values, losing accuracy very quickly:

<?php
$a
= 1.234
$b
= 2.345
$c
= 7.890

$ab
= bcmul($a,$b);           // 2
$abc = bcmul($ab,$c);

echo
$abc;                 // 15
?>

... compare with the answer you get when you use more decimal places:

<?php
$a
= 1.234
$b
= 2.345
$c
= 7.890

bcscale
(15);
$ab = bcmul($a,$b);           // 2.893730
$abc = bcmul($ab,$c);

echo
$abc;                 // 22.83152970
?>
up
-4
ravenswd at gmail dot com
5 years ago
Simple, easy way to remove excess trailing zeros using rtrim:
<php>
  // $total is the result of a bcmath calculation
  if ( strpos($total, '.') !== false ):
    $total = rtrim($total, '0');
    $total = rtrim($total, '.');
  endif;
</php>
up
-4
rastislav dot bostik at bwd21 dot cz
5 years ago
Previously stated one liner trailing 0 removing using rtrim() works fine except following class of subcases:

<?php
echo rtrim('100.0000', '0.'); // 1 instead 100
echo rtrim('1230.00000000', '0.'); // 123 instead 1230
?>

What seems to be working to me is using regular expression replacement. Althought it`s probably not that fast as rtrim(), I hope it should be more reliable:

<?php
function removeFloatNumStringZeroTrailer($input) {
   
$patterns = array('/[\.][0]+$/','/([\.][0-9]*[1-9])([0]*)$/');
   
$replaces = array('','$1');
    return
preg_replace($patterns,$replaces,$input);
}

echo
removeFloatNumStringZeroTrailer('100.0000'); // says 100
echo removeFloatNumStringZeroTrailer('1230.00000000'); // says 1230
?>
up
-6
nemesarial at gmail dot com
2 years ago
To remove trailing zeros when using large bcscale number can be done by casting to float when ready to display the number.

<?php
bcscale
(15);
$a=123.456;
$b=0.123;

$_ab=bcadd($a,$b);
echo
$_ab;
// 123.579000000000000

$ab = (float)$_ab;
echo
$ab;
// 123.579

?>
To Top