从 .txt 文件中读取特定行

Question

尝试从 .txt 文件中读取一行，然后根据该行上的内容编写 if 语句。我写了我认为应该工作的内容，它打印出该行，但 if 语句打印出“此行是假的”import linecachetest = open('test.txt', 'w+')test.write('Test\n')test.write('True\n')test.close()read = linecache.getline('test.txt', 2)print(read)if read == 'True':    print("The line is True")else:    print('The line is False')结果：真的这条线是假的

Answer 1

这是一个快速解释：

import linecache

test = open('test.txt', 'w+')

test.write('Test\n')

test.write('True\n')

test.close()

read = linecache.getline('test.txt', 2)

# At this moment read has 'True\n' as value

print(read)

# However print formats the output with the special character. Hence your print 

will have a line return try print(read+read) to see

if read == 'True': # This evaluate to False

    print("The line is True")

else: #Well this is an else, you should avoid doing so if you have a binary condition. Writing elif read == 'False' is not too bad

    print('The line is False')

另外，我的回答是指出为什么它没有按照您的怀疑行事。请参阅有关 str.strip() 的文档：https ://docs.python.org/2/library/stdtypes.html#str.strip

Answer 2

问题（如第一条评论所建议的那样是换行符。在 [2] 中：读出 [2]：'True\n'

要修复它，您可以： if read.rstrip() == 'True': print("The line is True") else: print('The line is False')

此外，仅当您因大文件而遇到性能问题时，我才会使用 linecache。否则使用 open('test.txt').readlines()[-1]

获取最后一行