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

 ?>

用户评论:

[#1] nemesarial at gmail dot com [2015-07-02 10:45:17]

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 ?>

[#2] herslyadam at gmail dot com [2014-04-07 22:04:30]

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); } ?>

[#3] ravenswd at gmail dot com [2012-04-30 18:43:26]

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>

[#4] rastislav dot bostik at bwd21 dot cz [2012-01-25 14:20:59]

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 ?>

[#5] mwgamera at gmail dot com [2007-12-05 18:45:50]

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); } ?>

[#6] invincible at limitedintelligence dot com [2006-02-08 03:50:47]

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 ?>