bcsub()

(PHP 4, PHP 5, PHP 7)

2个任意精度数字的减法

说明

bcsub(string $left_operand,string $right_operand[,int $scale= int]): string

左操作数减去右操作数.

参数

$left_operand

字符串类型的左操作数.

$right_operand

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。

返回值

返回减法之后结果为字符串类型.

范例

bcsub() example

<?php
$a = '1.234';
$b = '5';
echo bcsub($a, $b);     // -3
echo bcsub($a, $b, 4);  // -3.7660
?>

参见

• bcadd()2个任意精度数字的加法计算

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.

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.