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bcadd

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

bcadd两个任意精度数字的加法计算

说明

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

num1num2 求和。

参数

num1

左操作数,字符串类型。

num2

右操作数,字符串类型。

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

以字符串返回两个操作数求和之后的结果。

更新日志

版本 说明
8.0.0 现在 scale 可以为 null。

示例

示例 #1 bcadd() 示例

<?php

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

echo
bcadd($a, $b); // 6
echo bcadd($a, $b, 4); // 6.2340

?>

参见

  • bcsub() - 两个任意精度数字的减法

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User Contributed Notes 2 notes

up
20
Nitrogen
14 years ago
I made this to add an unlimited size of numbers together..

This could be useful for those without the BCMath extension.

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

<?php

function Add($Num1,$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');

// this is where the result is stored
$Output=array();

// 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'):'';

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

// if $Scale is null, automatically set it to the amount of decimal places for accuracy
if($Scale==null) $Scale=$DLen;

// remove leading zeroes and reverse the whole numbers, then append padded decimals on the end
$Num1=strrev(ltrim($Tmp1[1],'0').str_pad($Dec1,$DLen,'0'));
$Num2=strrev(ltrim($Tmp2[1],'0').str_pad($Dec2,$DLen,'0'));

// calculate the longest length we need to process
$MLen=max(strlen($Num1),strlen($Num2));

// pad the two numbers so they are of equal length (both equal to $MLen)
$Num1=str_pad($Num1,$MLen,'0');
$Num2=str_pad($Num2,$MLen,'0');

// process each digit, keep the ones, carry the tens (remainders)
for($i=0;$i<$MLen;$i++) {
$Sum=((int)$Num1{$i}+(int)$Num2{$i});
if(isset(
$Output[$i])) $Sum+=$Output[$i];
$Output[$i]=$Sum%10;
if(
$Sum>9) $Output[$i+1]=1;
}

// convert the array to string and reverse it
$Output=strrev(implode($Output));

// substring the decimal digits from the result, pad if necessary (if $Scale > amount of actual decimals)
// next, since actual zero values can cause a problem with the substring values, if so, just simply give '0'
// next, append the decimal value, if $Scale is defined, and return result
$Decimal=str_pad(substr($Output,-$DLen,$Scale),$Scale,'0');
$Output=(($MLen-$DLen<1)?'0':substr($Output,0,-$DLen));
$Output.=(($Scale>0)?".{$Decimal}":'');
return(
$Output);
}

$A="5650175242.508133742";
$B="308437806.831153821478770";

printf(" Add(%s,%s);\r\n// %s\r\n\r\n",$A,$B, Add($A,$B));
printf("BCAdd(%s,%s);\r\n// %s\r\n\r\n",$A,$B,BCAdd($A,$B));

/*
This will produce the following..
Add(5650175242.508133742,308437806.831153821478770);
// 5958613049.33928756347877

BCAdd(5650175242.508133742,308437806.831153821478770);
// 5958613049
*/

?>

It was a fun experience making, and thought I'd share it.
Enjoy,
Nitrogen.
up
9
Bo Anders Svensson
18 years ago
Be aware:

$exp1 = "1E5";
$exp2 = "2E4";

$ans1 = bcadd((float)$exp1, (float)$exp2, 3);
$ans2 = bcadd((int)$exp1, (int)$exp2, 3);
$ans3 = bcadd($exp1, $exp2, 3);

echo "1: $exp1 + $exp2 = $ans1\r\n";
echo "2: $exp1 + $exp2 = $ans2\r\n";
echo "3: $exp1 + $exp2 = $ans3\r\n";

1: 1E5 + 2E4 = 120000.000
2: 1E5 + 2E4 = 3.000
3: 1E5 + 2E4 = 0.000
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