什么是“B”字符字符串文字的前面呢？ [英] What does the 'b' character do in front of a string literal?

问题描述

显然，以下是有效的语法...

Apparently, the following is valid syntax...

my_string = b'The string'

我想知道......

I would like to know...

1. 这是什么 B 盈字符的字符串意味着什么？


2. 什么是使用它的影响？


3. 什么是用它适当的场合。

1. What does this b character infront of the string mean?
2. What are the effects of using it?
3. What are appropriate situations to use it.

我发现了一个相关问题就在这里SO但问题是关于PHP虽然并陈述了 b 用于指示该字符串是二进制的，而不是单向code这是需要code是从PHP＆LT版本兼容; 6移植到PHP 6时，我不认为这也适用于Python的。

I found a related question right here on SO but that question is about PHP though and it states the b is used to indicate the string is binary as opposed to unicode which was needed for code to be compatible from version of PHP < 6 when migrating to PHP 6. I don't think this applies to Python.

我没有找到蟒网站上的这个文档关于使用 U 在相同的语法字符来指定一个字符串作为单code。遗憾的是它并没有提到在乙字符的任意位置在该文件中

I did find this documentation on the python site about using a u character in the same syntax to specify a string as unicode. Unfortunately it doesn't mention the b character anywhere in that document.

此外，只是出于好奇，有没有比更多符号B 和 U 即做其他事情？

Also, just out of curiosity, are there more symbols than the b and u that do other things?

推荐答案

要报价了Python 2 .X文档：

'b'或'B'的preFIX中被忽略
  Python 2中;它表明
  文字应该成为一个字节的文字
  在Python 3（例如，当code是
  与2to3的自动转换）。一个
  'U'或'B'preFIX可以跟随
  一个'R'preFIX。

A prefix of 'b' or 'B' is ignored in Python 2; it indicates that the literal should become a bytes literal in Python 3 (e.g. when code is automatically converted with 2to3). A 'u' or 'b' prefix may be followed by an 'r' prefix.

借助的Python 3.3文档规定：

字节的文字总是prefixed以'b'或'B';他们生产字节的实例类型，而不是海峡的类型。他们可能只包含ASCII字符;具有128或更高的数值字节必须与逃逸pssed前$ P $。

Bytes literals are always prefixed with 'b' or 'B'; they produce an instance of the bytes type instead of the str type. They may only contain ASCII characters; bytes with a numeric value of 128 or greater must be expressed with escapes.

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