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|null $scale = null ) : string

对 num1 和 num2 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。

范例

Example #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

User Contributed Notes

Nitrogen 15-Jul-2009 09:16


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.

Bo Anders Svensson 23-May-2005 05:25


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