python3实现全角和半角字符转换的方法示例

前言

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一、背景介绍

解决什么问题：快速方便的对文本进行全角半角自动转换

适用什么场景：学生答题数据中全角字符替换为半角字符

二、全角半角原理

全角即：Double Byte Character，简称DBC

半角即：Single Byte Character，简称SBC

在 windows 中，中文和全角字符都占两个字节，并且使用了 asciichart 2 (codes 128–255)；
全角字符的第一个字节总是被置为 163，而第二个字节则是相同半角字符码加上128（不包括空格，全角空格和半角空格也要考虑进去）；

对于中文来说，它的第一个字节被置为大于163，如'阿'为:176 162，检测到中文时不进行转换。

例如：半角 a 为 65，则全角 a 是 163（第一个字节）、193（第二个字节，128+65）。

全角半角示例：（文本 test.txt 包含全角和半角字符）

F:\test>type test.txt
123456
１２３４５６
abcdefg
ａｂｃｄｅｆｇ
中国你好

三、使用 Python3 实现全角半角转换

# -*- coding:utf-8 -*-
# i@mail.chenpeng.info

”'
全角即：Double Byte Character，简称：DBC
半角即：Single Byte Character，简称：SBC
”'

def DBC2SBC(ustring):
”' 全角转半角 ”'
rstring = “”
for uchar in ustring:
 inside_code = ord(uchar)
 if inside_code == 0x3000:
 inside_code = 0x0020
 else:
 inside_code -= 0xfee0
 if not (0x0021 <= inside_code and inside_code <= 0x7e):
  rstring += uchar
  continue
 rstring += chr(inside_code)
return rstring

def SBC2DBC(ustring):
”' 半角转全角 ”'
rstring = “”
for uchar in ustring:
 inside_code = ord(uchar)
 if inside_code == 0x0020:
 inside_code = 0x3000
 else:
 if not (0x0021 <= inside_code and inside_code <= 0x7e):
  rstring += uchar
  continue
 inside_code += 0xfee0
 rstring += chr(inside_code)
return rstring

s = ”'
array(‘０' => ‘0', ‘１' => ‘1', ‘２' => ‘2', ‘３' => ‘3', ‘４' => ‘4',
 ‘５' => ‘5', ‘６' => ‘6', ‘７' => ‘7', ‘８' => ‘8', ‘９' => ‘9',
 ‘Ａ' => ‘A', ‘Ｂ' => ‘B', ‘Ｃ' => ‘C', ‘Ｄ' => ‘D', ‘Ｅ' => ‘E',
 ‘Ｆ' => ‘F', ‘Ｇ' => ‘G', ‘Ｈ' => ‘H', ‘Ｉ' => ‘I', ‘Ｊ' => ‘J',
 ‘Ｋ' => ‘K', ‘Ｌ' => ‘L', ‘Ｍ' => ‘M', ‘Ｎ' => ‘N', ‘Ｏ' => ‘O',
 ‘Ｐ' => ‘P', ‘Ｑ' => ‘Q', ‘Ｒ' => ‘R', ‘Ｓ' => ‘S', ‘Ｔ' => ‘T',
 ‘Ｕ' => ‘U', ‘Ｖ' => ‘V', ‘Ｗ' => ‘W', ‘Ｘ' => ‘X', ‘Ｙ' => ‘Y',
 ‘Ｚ' => ‘Z', ‘ａ' => ‘a', ‘ｂ' => ‘b', ‘ｃ' => ‘c', ‘ｄ' => ‘d',
 ‘ｅ' => ‘e', ‘ｆ' => ‘f', ‘ｇ' => ‘g', ‘ｈ' => ‘h', ‘ｉ' => ‘i',
 ‘ｊ' => ‘j', ‘ｋ' => ‘k', ‘ｌ' => ‘l', ‘ｍ' => ‘m', ‘ｎ' => ‘n',
 ‘ｏ' => ‘o', ‘ｐ' => ‘p', ‘ｑ' => ‘q', ‘ｒ' => ‘r', ‘ｓ' => ‘s',
 ‘ｔ' => ‘t', ‘ｕ' => ‘u', ‘ｖ' => ‘v', ‘ｗ' => ‘w', ‘ｘ' => ‘x',
 ‘ｙ' => ‘y', ‘ｚ' => ‘z',
 ‘（' => ‘(‘, ‘）' => ‘)', ‘〔' => ‘[‘, ‘〕' => ‘]', ‘【' => ‘[‘,
 ‘】' => ‘]', ‘〖' => ‘[‘, ‘〗' => ‘]', ‘”‘ => ‘[‘, ‘”‘ => ‘]',
 ‘\” => ‘[‘, ‘\” => ‘]', ‘｛' => ‘{‘, ‘｝' => ‘}', ‘《' => ‘<‘,
 ‘》' => ‘>',
 ‘％' => ‘％', ‘＋' => ‘+', ‘—' => ‘-‘, ‘－' => ‘-‘, ‘～' => ‘-‘,
 ‘：' => ‘:', ‘。' => ‘.', ‘、' => ‘,', ‘，' => ‘.', ‘、' => ‘.',
 ‘；' => ‘,', ‘？' => ‘?', ‘！' => ‘!', ‘…' => ‘-‘, ‘‖' => ‘|',
 ‘”‘ => ‘”‘, ‘\” => ‘`', ‘\” => ‘`', ‘｜' => ‘|', ‘〃' => ‘”‘,
 ‘' => ‘ ‘);
 ”'

# 全角转半角
print(DBC2SBC(s))

# 半角转全角
print(SBC2DBC(s))

s = ”'中文测试”'

# 全角转半角
print(DBC2SBC(s))

# 半角转全角
print(SBC2DBC(s))

四、总结

五、参考资料

http://thinkerou.com/2015-06/covert-dbc-sbc/

来源：http://chenpeng.info/html/3795