使用正则表达式替换文件中的字符串

Question

如何用Python中的正则表达式替换文件中的字符串？

我想打开一个文件，在这个文件中我应该将字符串替换为其他字符串，我们需要使用正则表达式(搜索和替换)。打开文件并将其与搜索和替换方法一起使用的示例是什么？

Answer 1

# The following code will search 'MM/DD/YYYY' (e.g. 11/30/2016 or NOV/30/2016, etc ),
# and replace with 'MM-DD-YYYY' in multi-line mode.
import re
with open ('input.txt', 'r' ) as f:
    content = f.read()
    content_new = re.sub('(\d{2}|[a-yA-Y]{3})\/(\d{2})\/(\d{4})', r'\1-\2-\3', content, flags = re.M)

Answer 2

这是一种通用格式。您可以根据您的需求使用re.sub或re.match。下面是打开并执行文件的一般模式：

import re

input_file = open("input.h", "r")
output_file = open("output.h.h", "w")
br = 0
ot = 0

for line in input_file:
    match_br = re.match(r'\s*#define .*_BR (0x[a-zA-Z_0-9]{8})', line) # Should be your regular expression
    match_ot = re.match(r'\s*#define (.*)_OT (0x[a-zA-Z_0-9]+)', line) # Second regular expression

if match_br:
    br = match_br.group(1)
    # Do something

elif match_ot:
    ot = match_ot.group(2)
    # Do your replacement

else:
    output_file.write(line)