问题描述
在python2中:
$ python2 -c 'print "\x08\x04\x87\x18"' | hexdump -C
00000000 08 04 87 18 0a |.....|
00000005
在python3中:
$ python3 -c 'print("\x08\x04\x87\x18")' | hexdump -C
00000000 08 04 c2 87 18 0a |......|
00000006
为什么这里有字节"\xc2"
?
修改:
我认为当字符串中包含非ASCII字符时,python3会将字节"\xc2"
附加到字符串中. (如@Ashraful伊斯兰教所说的)
I think when the string have a non-ascii character, python3 will append the byte "\xc2"
to the string. (as @Ashraful Islam said)
那么如何在python3中避免这种情况?
So how can I avoid this in python3?
推荐答案
请考虑以下代码段:
import sys
for i in range(128, 256):
sys.stdout.write(chr(i))
使用Python 2运行此代码,然后使用hexdump -C
查看结果:
Run this with Python 2 and look at the result with hexdump -C
:
00000000 80 81 82 83 84 85 86 87 88 89 8a 8b 8c 8d 8e 8f |................|
等等不出意外;从0x80
到0xff
的128个字节.
Et cetera. No surprises; 128 bytes from 0x80
to 0xff
.
使用Python 3进行相同的操作
Do the same with Python 3:
00000000 c2 80 c2 81 c2 82 c2 83 c2 84 c2 85 c2 86 c2 87 |................|
...
00000070 c2 b8 c2 b9 c2 ba c2 bb c2 bc c2 bd c2 be c2 bf |................|
00000080 c3 80 c3 81 c3 82 c3 83 c3 84 c3 85 c3 86 c3 87 |................|
...
000000f0 c3 b8 c3 b9 c3 ba c3 bb c3 bc c3 bd c3 be c3 bf |................|
总结:
- 从
0x80
到0xbf
的所有内容都以0xc2
开头. - 从
0xc0
到0xff
的所有内容都将第6位设置为零,并在前面加上0xc3
.
- Everything from
0x80
to0xbf
has0xc2
prepended. - Everything from
0xc0
to0xff
has bit 6 set to zero and has0xc3
prepended.
那么,这是怎么回事?
在Python 2中,字符串是ASCII,并且不进行任何转换.告诉给在0-127 ASCII范围之外的地方写东西,上面写着"okey-doke!".和只是写那些字节.很简单.
In Python 2, strings are ASCII and no conversion is done. Tell it towrite something outside the 0-127 ASCII range, it says "okey-doke!" andjust writes those bytes. Simple.
在Python 3中,字符串为 Unicode .当非ASCII字符是编写时,必须以某种方式对其进行编码.默认编码是UTF-8.
In Python 3, strings are Unicode. When non-ASCII characters arewritten, they must be encoded in some way. The default encoding isUTF-8.
那么,这些值如何用UTF-8编码?
So, how are these values encoded in UTF-8?
从0x80
到0x7ff
的代码点编码如下:
Code points from 0x80
to 0x7ff
are encoded as follows:
110vvvvv 10vvvvvv
其中11个v
字符是代码点的位.
Where the 11 v
characters are the bits of the code point.
因此:
0x80 hex
1000 0000 8-bit binary
000 1000 0000 11-bit binary
00010 000000 divide into vvvvv vvvvvv
11000010 10000000 resulting UTF-8 octets in binary
0xc2 0x80 resulting UTF-8 octets in hex
0xc0 hex
1100 0000 8-bit binary
000 1100 0000 11-bit binary
00011 000000 divide into vvvvv vvvvvv
11000011 10000000 resulting UTF-8 octets in binary
0xc3 0x80 resulting UTF-8 octets in hex
这就是为什么在87
之前获得c2
的原因.
So that’s why you’re getting a c2
before 87
.
如何在Python 3中避免所有这些?使用bytes
类型.
How to avoid all this in Python 3? Use the bytes
type.
这篇关于为什么python2和python3中的print输出使用相同的字符串不同?的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持!