c# - 为什么转换这个指数会抛出 FormatException？

Question

为什么这个指数在使用 Decimal.Parse 转换为小数时会抛出 FormatException。

String stringValue = "8.83080183680678E-05";
Decimal decimalValue = Decimal.Parse(badValue, NumberStyles.AllowExponent);

当代码执行时抛出一个FormatException

"Input string was not in a correct format."

代码似乎遵守 MSDN spec : [ws][$][sign][digits,]digits[.fractional-digits][e[sign]digits][ws]

Answer 1

您需要指定数字格式也允许小数。

Decimal.Parse(badValue, NumberStyles.AllowExponent | NumberStyles.AllowDecimalPoint);

...在 AllowExponent 的文档中有解释:

Indicates that the numeric string can be in exponential notation. The AllowExponent flag allows the parsed string to contain an exponent that begins with the "E" or "e" character and that is followed by an optional positive or negative sign and an integer. In other words, it successfully parses strings in the form nnnExx, nnnE+xx, and nnnE-xx. It does not allow a decimal separator or sign in the significand or mantissa; to allow these elements in the string to be parsed, use the AllowDecimalPoint and AllowLeadingSign flags, or use a composite style that includes these individual flags.

NumberStyles.Float 在这种情况下可能是更好的选择。