bcsub

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

bcsub — 两个任意精度数字的减法

说明

bcsub(string $num1, string $num2, ?int $scale = null): string

num1 减去 num2。

参数

num1: 字符串类型的左操作数。
num2: 字符串类型的右操作数。
scale: 此可选参数用于设置结果中小数点后的小数位数。也可通过使用 bcscale() 来设置全局默认的小数位数，用于所有函数。如果未设置，则默认为 0。

返回值

以 string 类型返回减法之后的结果。

更新日志

版本	说明
8.0.0	现在 `scale` 可以为 null。

示例

示例 #1 bcsub() 示例

<?php

$a = '1.234';
$b = '5';

echo bcsub($a, $b);     // -3
echo bcsub($a, $b, 4);  // -3.7660

?>

参见

bcadd() - 两个任意精度数字的加法计算

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用户贡献的备注 2 notes

down

nd at snackbox dot org ¶

6 years ago

The parameter order here is probably fairly obvious to most people (subtract right from left), but to clarify with a simple use case since I was struggling with this at the end of a long day:

<?php
echo bcsub('7', '5'); // 7 - 5 = '2'
echo bcsub('12', '17'); // 12 - 17 = '-5'
?>

Provide the parameters in the same order you would when using a normal subtraction operator.

down

charles dot adrian dot wood at gmail dot com ¶

5 years ago

Please note that bcsub will fail in non-obvious ways if it's fed something that cannot be converted to a number. For instance:

bcsub('yes', 'no') === '0'

Yes, if you put garbage in, you get garbage out. Just don't expect bcsub to throw an error when you feed it an entirely non-numeric value.