将包含科学计数形式的数字的字符串转换为PHP中的double [英] Convert a string containing a number in scientific notation to a double in PHP

问题描述

我需要帮助，将包含科学计数形式的数字的字符串转换为双精度字符.

I need help converting a string that contains a number in scientific notation to a double.

示例字符串: "1.8281e-009" "2.3562e-007" "0.911348"

Example strings: "1.8281e-009" "2.3562e-007" "0.911348"

我正在考虑将数字分解为左边的数字和指数，而不是通过数学运算来生成数字；但是有更好的/标准的方法来做到这一点吗?

I was thinking about just breaking the number into the number on the left and the exponent and than just do the math to generate the number; but is there a better/standard way to do this?

推荐答案

PHP是无类型动态类型的，这意味着它必须解析值来确定其类型(最新版本的PHP具有类型声明).

PHP is typeless dynamically typed, meaning it has to parse values to determine their types (recent versions of PHP have type declarations).

在您的情况下，您可以简单地执行数字运算以强制PHP将值视为数字(并且它理解科学计数法x.yE-z).

In your case, you may simply perform a numerical operation to force PHP to consider the values as numbers (and it understands the scientific notation x.yE-z).

尝试一下

  foreach (array("1.8281e-009","2.3562e-007","0.911348") as $a)
  {
    echo "String $a: Number: " . ($a + 1) . "\n";
  }

只加1(也可以减去零)将使字符串变成数字，并带有正确的小数位数.

just adding 1 (you could also subtract zero) will make the strings become numbers, with the right amount of decimals.

结果:

  String 1.8281e-009: Number: 1.0000000018281
  String 2.3562e-007: Number: 1.00000023562
  String 0.911348:    Number: 1.911348

您也可以使用(float)

  $real = (float) "3.141592e-007";

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