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C＃中浮点数和double数据类型的实际范围是什么？

[英]What are the actual ranges of floating point and double data types in C#?

原文 2013-07-20 06:47:40 9 2 c#/ types/ floating-point/ double

I'm learning C# and trying to get a logical visual representation of the actual range of data types in C#. 我正在学习C＃，并试图获得C＃中数据类型实际范围的逻辑可视表示。

I have moved through the integers and am now up to float and double data types. 我已经遍历整数，现在可以使用浮点数和双精度数据类型。

8 bits (1 byte), sbyte, -128 to 127. 8位（1字节），字节，-128至127。
8 bits (1 byte), byte, 0 to 255. 8位（1字节），字节，0至255。
16 bits (2 bytes), short, -32,768 to 32,767. 16位（2字节），短，-32,768至32,767。
16 bits (2 bytes), ushort, 0 to 65535. 16位（2个字节），ushort，0至65535。
32 bits (4 bytes), int, -2,147,483,648 to 2,147,483,647. 32位（4字节）int -2,147,483,648至2,147,483,647。
32 bits (4 bytes), uint, 0 to 4,294,967,295. 32位（4字节），uint，0至4,294,967,295。
64 bits (8 bytes), long, -9,223,372,036,854,775,808 to 9,223,372,036,854,775,807 64位（8字节），长-9,223,372,036,854,775,808至9,223,372,036,854,775,807
64 bits (8 bytes), ulong, 0 to 18,446,744,073,709,551,615. 64位（8字节），ulong，0至18,446,744,073,709,551,615。

Here are the references to float and double data types sizes at msdn: 以下是msdn上对float和double数据类型大小的引用：

Float: http://msdn.microsoft.com/en-us/library/b1e65aza(v=vs.110).aspx 浮动： http ： //msdn.microsoft.com/zh-CN/library/b1e65aza（ v = vs.110）.aspx

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Double: http://msdn.microsoft.com/en-us/library/678hzkk9.aspx 双： http : //msdn.microsoft.com/en-us/library/678hzkk9.aspx

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So, trying to keep with the convention of specifiying the actual range of numbers as in the numbered list above, what do these two ranges actually represent? 因此，尝试按照上面编号列表中指定数字的实际范围的惯例，这两个范围实际上代表什么？

2 个解决方案

The ranges are actually –infinity to +infinity. 范围实际上是–无限到+无限。

The largest finite float is 340282346638528859811704183484516925440. This is 2 ¹²⁸ –2 ^128–24 . 最大的有限 float是340282346638528859811704183484516925440。这是2 ¹²⁸ –2 ^128–24 。

The largest finite double is 179769313486231570814527423731704356798070567525844996598917476803157260780028538760589558632766878171540458953514382464234321326889464182768467546703537516986049910576551282076245490090389328944075868508455133942304583236903222948165808559332123348274797826204144723168738177180919299881250404026184124858368. This is 2 ¹⁰²⁴ –2 ^1024–53 . 最大的有限 double是179769313486231570814527423731704356798070567525844996598917476803157260780028538760589558632766878171540458953514382464234321326889464182768467546703537516986049910576551282076245490090389328944075868508455133942304583236903222948165808559332123348274797826204144723168738177180919299881250404026184124858368.这是2 ¹⁰²⁴ -2 ^{一零二四年至1053年} 。

The ranges are represented in "exponential format" for conciseness. 为简洁起见，范围以“指数格式”表示。 For example, +1.7e+308 means 17 followed by 307 zeros: 例如，+ 1.7e + 308表示17，后跟307个零：

1,700,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000 1,700,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000,000

So the exponential format is preferred for such large numbers. 因此，指数格式适用于如此大的数字。 And the same goes for extremely small numbers. 对于极小的数字也是如此。

Also, take a look at this reading by Jon Skeet. 另外，请看乔恩·斯基特（Jon Skeet）的读物。