Python中的类型 [英] Typecasting in Python

问题描述

我需要将Python中的字符串转换为其他类型，例如无符号和有符号的8,16,32和64位int，双精度浮点数和字符串。

I need to convert strings in Python to other types such as unsigned and signed 8, 16, 32, and 64 bit ints, doubles, floats, and strings.

推荐答案

您可以将字符串转换为32位有符号整数与 int function：

You can convert a string to a 32-bit signed integer with the int function:

str = "1234"
i = int(str)  // i is a 32-bit integer

如果字符串不表示整数，获取 ValueError 异常。但请注意，如果字符串表示一个整数，但该整数不适合32位有符号int，那么你实际上会得到一个类型 long 。

If the string does not represent an integer, you'll get a ValueError exception. Note, however, that if the string does represent an integer, but that integer does not fit into a 32-bit signed int, then you'll actually get an object of type long instead.

然后，您可以用一些简单的数学将其转换为其他宽度和签名：

You can then convert it to other widths and signednesses with some simple math:

s8 = (i + 2**7) % 2**8 - 2**7      // convert to signed 8-bit
u8 = i % 2**8                      // convert to unsigned 8-bit
s16 = (i + 2**15) % 2**16 - 2**15  // convert to signed 16-bit
u16 = i % 2**16                    // convert to unsigned 16-bit
s32 = (i + 2**31) % 2**32 - 2**31  // convert to signed 32-bit
u32 = i % 2**32                    // convert to unsigned 32-bit
s64 = (i + 2**63) % 2**64 - 2**63  // convert to signed 64-bit
u64 = i % 2**64                    // convert to unsigned 64-bit

您可以将字符串转换为浮点， code> float 函数：

You can convert strings to floating point with the float function:

f = float("3.14159")

Python浮动是其他语言引用的 double 即它们是64位。 Python中没有32位浮动广告。

Python floats are what other languages refer to as double, i.e. they are 64-bits. There are no 32-bit floats in Python.

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