问题描述
我一直在寻找将指数数字字符串转换为精确数字的方法.所以，我在 MySQL 中以字符串形式存储了一个指数数字.我想以确切的数字转换回这个字符串.但是这个数字好像很大，越界了，给我提供了错误的数据.
I've been searching for converting my exponential number string into an exact number.So, I've an exponential number stored as string in MySQL. I want to convert back this string in the exact number.But It seems the number is quite big and crosses the boundary and provide me wrong data.
虽然我尝试以下各种格式的代码，但结果格式不正确.
While I tried following code in various format but result is not in proper format.
policy_number = "2.9992020830803E+18";
number_format($policy_number, 0,'.','');
// Output
2999202083080300032
(float) $policy_number;
// Output
2.9992020830803E+18
sscanf($policy_number, "%f")[0];
// Output
2.9992020830803E+18
floatval($policy_number);
// Output
2.9992020830803E+18
gmp_init("2.9992020830803E+18");
gmp_strval($policy_number);
// Output
0
"2.9992020830803E+18" + 0;
// Output
2.9992020830803E+18
请告诉我正确的转换方法.
Please show me the right way to convert it.
推荐答案
更新
我同意 Ed Cottrell 的观点，即您的问题是如何将数据存储在数据库中.但是，如果这是一个您已经在查看已存储为指数的大量数据的项目，那么我编写的这个函数应该适合您.它应该适用于正负底数和指数.它基本上模仿了您手动操作的方式.
I agree with Ed Cottrell that your problem is how you are storing your data in the db. However, if this is a project where you are already looking at a large set of data that is already stored as an exponent then this function I wrote should work for you. It should work for positive and negative bases and exponents. It basically mimics the way you would do the operation by hand.
我无法找到使用数学函数的方法.如果有人知道如何做得更好，请发布.与此同时，我写这篇文章很开心.
I was not able to figure out a way to do it using math functions. If someone knows how to do it better please post. In the meantime, I had fun writing this.
希望能帮到你！
function getRealNumber($number){
//Parse the base and exponent.
preg_match('/^(.*?)E[\-|\+](.*?)$/', $number, $data);
$base = $data[1];
$exp = $data[2];
//Test to see if the base is negative.
if(preg_match('/\-/', $base)){
$base = str_replace('-', '', $base);
$isNegative = TRUE;
}
//Capture the offset of the decimal point.
preg_match('/\./', $base, $position, PREG_OFFSET_CAPTURE);
$offset = $position[0][1]; //This is the offset of the decimal point.
$string = str_replace('.', '', $base); //Get numbers without decimal.
$length = strlen($string); //Get the length of string.
//Test to see if we are adding zeros to the end or beginning of string.
if(preg_match('/E\+/', $number)){
//Let's move the decimal.
if($length > ($exp + $offset)){
$string = substr_replace($string, '.', ($exp + $offset), 0);
} else {
$string = $string . str_repeat('0', $exp - ($length - $offset));
}
}elseif(preg_match('/E\-/', $number)){
//Calculate the number of zeros needed to add and append them.
if($offset > $exp){
$string = substr_replace($string, '.', $offset, 0);
} else {
$string = '0.' . str_repeat('0', $exp - $offset) . $string;
}
}
//Add the negative sign if we need to.
if(!$isNegative){
return $string;
} else {
return '-' . $string;
}
}
$policy_number = "2.9992020830803E+18";
echo getRealNumber($policy_number);
//Will output 2999202083080300000
这篇关于在 PHP 中将完整字符串(以指数格式表示)转换回数字的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！