PHP 8.3.4 Released!

bccomp

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

bccomp比较两个任意精度的数字

说明

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

比较 num1num2, 并且返回整型数字的结果。

参数

num1

左边的运算数,是一个字符串。

num2

右边的运算数,是一个字符串。

scale

可选的 scale 参数被用作设置指示数字, 在使用来作比较的小数点部分。

返回值

两个数相等时返回 0; num1num2 大时返回 1; 其他则返回 -1。

更新日志

版本 说明
8.0.0 现在 scale 可以为 null。

示例

示例 #1 bccomp() 示例

<?php

echo bccomp('1', '2') . "\n"; // -1
echo bccomp('1.00001', '1', 3); // 0
echo bccomp('1.00001', '1', 5); // 1

?>
add a note

User Contributed Notes 9 notes

up
24
Robert Lozyniak
14 years ago
Beware that negative zero does not compare equal to positive zero.
up
13
aaugrin at gmail dot com
6 years ago
BEWARE! left and right operand is string!! so number in E-notation like 9.012E-6 need to be converted with sprintf('%F') to string
up
-3
m dot kaczanowski at alianet dot pl
15 years ago
Improvement of functions bcmax() and bcmin() originaly written by frank at booksku dot com

<?php

function bcmax() {
$args = func_get_args();
if (
count($args)==0) return false;
$max = $args[0];
foreach(
$args as $value) {
if (
bccomp($value, $max)==1) {
$max = $value;
}
}
return
$max;
}

function
bcmin() {
$args = func_get_args();
if (
count($args)==0) return false;
$min = $args[0];
foreach(
$args as $value) {
if (
bccomp($min, $value)==1) {
$min = $value;
}
}
return
$min;
}
?>
up
-12
Nitrogen
14 years ago
I made this to compare an unlimited size of numbers..

This could be useful for those without the BCMath extension.

It allows decimals, and option $Scale parameter. If $Scale isn't specified, then it'll automatically adjust to the correct number of decimals to compare.

<?php

function Comp($Num1,$Num2,$Scale=null) {
// check if they're valid positive numbers, extract the whole numbers and decimals
if(!preg_match("/^\+?(\d+)(\.\d+)?$/",$Num1,$Tmp1)||
!
preg_match("/^\+?(\d+)(\.\d+)?$/",$Num2,$Tmp2)) return('0');

// remove leading zeroes from whole numbers
$Num1=ltrim($Tmp1[1],'0');
$Num2=ltrim($Tmp2[1],'0');

// first, we can just check the lengths of the numbers, this can help save processing time
// if $Num1 is longer than $Num2, return 1.. vice versa with the next step.
if(strlen($Num1)>strlen($Num2)) return(1);
else {
if(
strlen($Num1)<strlen($Num2)) return(-1);

// if the two numbers are of equal length, we check digit-by-digit
else {

// remove ending zeroes from decimals and remove point
$Dec1=isset($Tmp1[2])?rtrim(substr($Tmp1[2],1),'0'):'';
$Dec2=isset($Tmp2[2])?rtrim(substr($Tmp2[2],1),'0'):'';

// if the user defined $Scale, then make sure we use that only
if($Scale!=null) {
$Dec1=substr($Dec1,0,$Scale);
$Dec2=substr($Dec2,0,$Scale);
}

// calculate the longest length of decimals
$DLen=max(strlen($Dec1),strlen($Dec2));

// append the padded decimals onto the end of the whole numbers
$Num1.=str_pad($Dec1,$DLen,'0');
$Num2.=str_pad($Dec2,$DLen,'0');

// check digit-by-digit, if they have a difference, return 1 or -1 (greater/lower than)
for($i=0;$i<strlen($Num1);$i++) {
if((int)
$Num1{$i}>(int)$Num2{$i}) return(1);
else
if((int)
$Num1{$i}<(int)$Num2{$i}) return(-1);
}

// if the two numbers have no difference (they're the same).. return 0
return(0);
}
}
}

$A="10.50002";
$B="10.50001";

printf(" Comp(%s,%s); // %s\r\n",$A,$B, Comp($A,$B));
printf("BCComp(%s,%s); // %s\r\n",$A,$B,BCComp($A,$B));

/*
Comp(10.50002,10.50001); // 1
BCComp(10.50002,10.50001); // 0 (BCComp has a default decimal scale of 0, unless specified)
*/

?>

I tried to make this behave like BCComp..

The only difference being mine will compare the decimals by default.. BCComp won't..
.. unless, of course, you specify the amount of decimals to include in the process.
Enjoy,
Nitrogen.
up
-11
Anonymous
19 years ago
Note that the above function defeats the purpose of BCMath functions, for it uses the 'conventional' < operator.
Instead, it should be:
<?php
function my_bccomp_zero($amount, $scale)
{
if (@
$amount{0}=="-")
{
return
bccomp($amount, '-0.0', $scale);
}
else
{
return
bccomp($amount, '0.0', $scale);
}
}
?>
up
-7
frank at booksku dot com
18 years ago
I slapped together min() and max() functions using bccomp(). While min() and max() only take an arbitrary number of args (i.e. max(1, 5, 1235, 12934, 66)) bccomp only takes 2.

Note that this doesn't take into account $scale.

<?php

function bcmax() {
$max = null;
foreach(
func_get_args() as $value) {
if (
$max == null) {
$max = $value;
} else if (
bccomp($max, $value) < 0) {
$max = $value;
}
}
return
$max;
}

function
bcmin() {
$min = null;
foreach(
func_get_args() as $value) {
if (
$min == null) {
$min = $value;
} else if (
bccomp($min, $value) > 0) {
$min = $value;
}
}
return
$min;
}
?>
up
-13
github.com/alixaxel/phunction/
11 years ago
You can wrap this function with version_compare() to have support for operators and friendlier (boolean) return values.

<?php

function _bccomp($a, $b, $operator = '=')
{
return
version_compare(bccomp($a, $b), 0, $operator);
}

var_dump(_bccomp(5, 3, '>=')); // true

?>

Still works with arbitrary length numbers.
up
-10
Artur Kuritsyn
6 years ago
bccomp - doesn't compare by default more then 16 characters

$number = '-4.444444444444444444444444444444444444444444445';
$precision = 16;
var_dump(bccomp(bcadd($number, '0', $precision), bcadd($number, '0', $precision+1)));

//outputs 0 on PHP 5.3

use strcomp
up
-17
simonrataj at seznam dot cz
7 years ago
In PHP 7, bccomp($a, $b) is the same as $a <=> $b.
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