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);