打印从字符串1到字符串2的后x行

Question

I'm trying to write a function that reads through a text file until it finds a word (say "hello"), then print the next x lines of string starting with string 1 (say "start_description") until string 2 (say "end_description").

hello

start_description 123456 end_description

The function should look like description("hello") and the following output should look like

123456

It's a bit hard to explain. I know how to find the certain word in the text file but I don't know how to print, as said, the next few lines between the two strings (start_description and end_description).

EDIT1: I found some code which allows to print the next 8, 9, ... lines. But because the text in between the two strings is of variable length, that does not work...

EDIT2: Basically it's the same question as in this post: Python: Print next x lines from text file when hitting string , but the range(8) does not work for me (see EDIT1).

The input file could look like:

HELLO
salut
A: 123456.

BYE
au revoir
A: 789123.

The code should then look like:

import re
def description(word):
    doc = open("filename.txt",'r')
    word = word.upper()

    for line in doc:
        if re.match(word,line):
            #here it should start printing all the text between start_description and end_description, for example 123456

    return output

print description("hello")
123456
print description("bye")
789123

Answer 1

Here's a way using split:

start_desc = 'hello'
end_desc = 'bye'
str = 'hello 12345\nabcd asdf\nqwer qwer  erty\n bye'

print str.split('hello')[1].split('bye')[0]

The first split will result in:

('', ' 12345\nabcd asdf\nqwer qwer  erty\n bye')

So feed the second element to the second split and it will result in:

('12345\nabcd asdf\nqwer qwer  erty\n ', '')

Use the first element.

You can then use strip() to remove the surrounding spaces if you wish.

Answer 2

def description(infilepath, startblock, endblock, word, startdesc, enddesc):
    with open(infilepath) as infile:
        inblock = False
        name = None
        found = False
        answer = []
        for line in infile:
            if found and not inblock: return answer
            if line.strip() != startblock and not inblock: continue
            if line.strip() == startblock: inblock = True
            elif line.strip() == endblock: inblock = False
            if not line.startswith(startdesc):
                name = line.strip()
                continue
            if name is not None and name != word: continue
            if not line.startswith(startdesc): continue
            answer.append(line.strip().lstrip(startdesc).rstrip(enddesc))