PHP Conference Nagoya 2025

bcscale

(PHP 4, PHP 5, PHP 7, PHP 8)

bcscaleSet or get default scale parameter for all bc math functions

Description

bcscale(int $scale): int

Sets the default scale parameter for all subsequent calls to bc math functions that do not explicitly specify a scale parameter.

bcscale(null $scale = null): int

Gets the current scale factor.

Parameters

scale

The scale factor.

Return Values

Returns the old scale when used as setter. Otherwise the current scale is returned.

Errors/Exceptions

This function throws a ValueError if scale is outside the valid range.

Changelog

Version Description
8.0.0 scale is now nullable.
7.3.0 bcscale() can now be used to get the current scale factor; when used as setter, it now returns the old scale value. Formerly, scale was mandatory, and bcscale() always returned true.

Examples

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

?>

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User Contributed Notes 4 notes

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23
mwgamera at gmail dot com
16 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);
}
?>
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16
sicerwork at aliyun dot com
7 years ago
Executing bcsacle() will change the scale value of fpm.conf, not only the current process.
up
6
ravenswd at gmail dot com
12 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
5
herslyadam at gmail dot com
10 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);
}
?>
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