如何使用正则表达式在 Python 3 中的特定字符串之后或之前找到一行？

Question

如何使用正则表达式在python3中的特定字符串之前或之后找到一行？我正在阅读文本文件中的内容，请帮助我文件.txtmy name is dharshinimy mom name is chandramy dad name is udaymy anniversay is on 04/01/1997import rewith open('file.txt','r') as f:input_file = f.readlines()for line in input_file : find_line = re.findall(r'(mom)', line) print(next-1(line)) print(next(line)) print(next(line))预期输出：my name is dharshinimy dad name is udaymy anniversay is on 04/01/1997

Answer 1

尝试使用enumerate,enumerate在循环时获取索引，因此我获取索引并通过索引和切片获取其余值：

for i,line in enumerate(paragraph):

    if 'mom' in line:

        print(paragraph[:i])

        print(paragraph[i:])

编辑：

with open('file.txt','r') as f:

    input_file = f.readlines()

    for i,line in enumerate(input_file):

        line=line.rstrip()

        if 'mom' in line:

            print(paragraph[:i])

            print(paragraph[i:])

Answer 2

试试这个：

import re

paragraph = ["my name is dharshini", "my mom name is chandra", "my dad name is uday" ,  "my anniversay is on 04/01/1997" ]

#set a flag for later

print_next = False

for line in paragraph:

 find_line = re.findall(r'(mom)', line)

 #if mom is found dad will be next

 if print_next:

     print(line)

     print_next = False

 #if mom is found

 if len(find_line) > 0:

     print(line)

     print_next = True