Question

此Python代码运行，但打印文本文件的最后一页。不知道为什么，但是我的目的是打印指定文本行（包含特定字符串** Direct **的行）下方的整行文本。如何遍历文本文件，在每一行中搜索指定的字符串，并在找到后立即在其下方打印行？我搜索了许多在线论坛，但没有找到一个易于理解的示例。我使用Python Sypder 2.7。任何帮助表示赞赏

import os
Path = '..\\Test.txt'

if os.path.isfile(Path): 
    with open(Path) as f:
        for line in f:
            print line
else:
    print Path, "doesn't exist"
f.close()

Answer 1

Python 3.x：

dummy.txt

Mango
Anday Wala Burger
40
Aloo
Anday
Ghobi
Anday Wala Burger
30
Kheerey
Anday Wala Burger

py：

searchString = 'Anday Wala Burger'    
with open('dummy.txt', "r") as input:
    try:
        for line in input:
            if searchString in line:
                print(next(input), end='')
    except StopIteration:
            pass

输出：

40
30

编辑：

Python 2.7：

dummyFile= "dummy.txt"
searchString = 'Anday Wala Burger'

with open(dummyFile) as f:
    content = f.readlines()

# you may also want to remove empty lines
content = [l.strip() for l in content if l.strip()]

# flag
nextLine = False

for line in content:

    if searchString in line:
        nextLine = not nextLine
    else:
        if nextLine:
            print(line)
            nextLine = not nextLine
        else:
            pass

输出：

40
30

Answer 2

检出re模块。它包含re.search()函数，该函数在字符串中搜索模式。

要打印下一行，可以使用f.next()来利用文件对象可迭代的事实。

例如，您可以这样做：

import os
import re

Path = 'foo.txt'
Pattern = "spam"  # String to be searched

if os.path.isfile(Path): 
    with open(Path) as f:
        for line in f:
            if re.search(Pattern, line):
                print(f.next())
else:
    print(Path, "doesn't exist")

顺便说一句，您不需要最后的f.close()。 with语句已经解决了这个问题。

Answer 3

检查one是否在文件的任何行中，并将找到的下一行打印为下一行，将打印的下一行打印为currentlineno+1

文件临时目录的内容

one
two
three
four

Python文件

with open('temp') as f:
   found=-1 
   #no lines are found to print so found is negative in value since line no in a file cannot be negative
   for index,line in enumerate(f):
        if found==index:
            print(line)
        if 'one' in line:
            found=index+1
            # when the condition is True found is set to the line no that we need to print

输出

two

Answer 4

您需要进行一些更改：

1.-阅读各行

2.-与您的文字进行比较

import os
Path = '..\\Test.txt'
look='**Direct**'

if os.path.isfile(Path): 
    with open(Path, "r") as f:
        for line in f:
            if look in line:
                print (line)
else:
    print (Path, "doesn't exist")

Python循环文本文件以查找和打印

4 个答案: