如何从python中的文本文件的特定行打印答案

【问题标题】：how to print from a particular line from text file in python如何从python中的文本文件的特定行打印
【发布时间】：2020-05-11 07:22:05
【问题描述】：

我正在使用此代码搜索一个特定的字符串：

stringToMatch = 'blah'
matchedLine = ''
#get line
with open(r'path of the text file', 'r') as file:
    for line in file:
        if stringToMatch in line:
            matchedLine = line
            break
#and write it to the file
with open(r'path of the text file ', 'w') as file:
    file.write(matchedLine)

即使字符串出现多次，它也只会打印一次。我还想在出现特定单词后打印所有行。我该怎么做？

【问题讨论】：

您的break 说一旦找到一个案例就离开for loop。您可能需要删除/修改它。

标签： python python-3.x text

【解决方案1】：

设置一个标志以跟踪您何时看到该行，并将这些行写入同一循环中的输出文件。

string_to_match = "blah"
should_print = False
with open("path of the text file", "r") as in_file, open("path of another text file", "w") as out_file:
    for line in in_file:
        if string_to_match in line:
            # Found a match, start printing from here on out
            should_print = True
        if should_print:
            out_file.write(line)

【讨论】：

【解决方案2】：

stringToMatch = 'blah'
matchedLine = ''

# get line
lines = ''
match = False
with open(r'path of the text file', 'r') as file:
    for line in file:
        if match:
            # store lines if matches before
            lines += line + '\n'
        elif stringToMatch in line:
            # If matches, just set a flag
            match = True

# and write it to the file
with open(r'path of the text file ', 'w') as file:
    file.write(lines)

【讨论】：

【解决方案3】：

你可以像这样修改你的代码：-

stringToMatch = 'blah'
matchedLine = ''
#get line
with open(r'path of the text file', 'r') as file:
    for line in file:
        if stringToMatch in line:
            matchedLine += line + '\n'

#and write it to the file
with open(r'path of the text file ', 'w') as file:
    file.write(matchedLine)

希望你明白了。

【讨论】：