python实现根据指定字符截取对应的行的内容

工作中遇到的，在一个.c文件中有很多函数，这个.c是自动生成的，需要将所有的函数通过extern放到.h中，每个函数都是UINT32 O_开头，通过正则表达式进行字符匹配以及通过linecache来截取特定行，代码如下：

#! /usr/bin/env python
# encoding:utf-8
# ! /usr/bin/env python
# encoding:utf-8
import re
import linecache
infile = 'D:\infile.txt'
outfile = 'D:\outfile.txt'
lineNumber = 1
with open(infile,'r') as f:
	number = []
	for line in f.readlines():
		m = re.findall(r"UINT32 O_\w+",line)  #匹配含有字符'UINT32 O_'的行
		if m:
			number.append(lineNumber)
		n = re.findall(r"OUT \w+",line) #假设只有一个OUT
		if n:
			number.append(lineNumber)
		lineNumber += 1
	with open(outfile, 'w+') as f_w:
		for j in range(len(number)):
			if j%2 == 0:
				start = number[j]
				end = number[j+1]
				destlines = linecache.getlines(file)[start-1:end] #截取start-end行的字符，不包括start-1,但包含end行
				f_w.write('extern ')
				for i in range(len(destlines)):
					if i != len(destlines)-1:
						f_w.write(destlines[i])
					else:
						f_w.write(destlines[i].replace('\n',';\n'))
				f_w.write('\n')

输入：

UINT32 O_FUNC1(UINT32 uwA,
IN UINT32 uwB,
IN UINT32* puwC,
IN UINT32* puwD,
OUT UINT32* puwE)
{
   //
}

　　输出：

extern UINT32 O_FUNC1(UINT32 uwA,
IN UINT32 uwB,
IN UINT32* puwC,
IN UINT32* puwD,
OUT UINT32* puwE);