問題描述
顯然，以下是有效的語法:
Apparently, the following is the valid syntax:
my_string = b'The string'
我想知道:
- 字符串前面的這個(gè)
b字符是什么意思? - 使用有什么效果?
- 在什么情況下使用合適?
我在 SO 上找到了一個(gè)相關(guān)問題，但這個(gè)問題是關(guān)于 PHP 的，它說明了 b 用于指示字符串是二進(jìn)制的，與 Unicode 不同，Unicode 是與 PHP 版本兼容所必需的.6，遷移到 PHP 6 時(shí).我認(rèn)為這不適用于 Python.
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.
我確實(shí)在 Python 網(wǎng)站上找到了關(guān)于使用u 字符以相同的語法將字符串指定為 Unicode.不幸的是，它沒有在該文檔的任何地方提及 b 字符.
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.
另外，出于好奇，有沒有比 b 和 u 更多的符號來做其他事情?
Also, just out of curiosity, are there more symbols than the b and u that do other things?
推薦答案
引用 Python 2.x 文檔:
'b' 或 'B' 的前綴在蟒蛇2；它表明文字應(yīng)該成為字節(jié)文字在 Python 3 中(例如，當(dāng)代碼用 2to3 自動轉(zhuǎn)換).一個(gè)'u' 或 'b' 前綴可以后跟'r' 前綴.
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.
Python 3 文檔 指出:
字節(jié)文字總是以'b'或'B'為前綴；它們生成 bytes 類型而不是 str 類型的實(shí)例.它們可能只包含 ASCII 字符；數(shù)值為 128 或更大的字節(jié)必須用轉(zhuǎn)義符表示.
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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