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，它打印出行，但是 if 语句打印出 'this line is false'

import linecache

test = 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：

正确

这条线是假的

Answer 1

这里有一个简单的解释：

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')

此外，我的回答是指出为什么它没有按照您所怀疑的那样运行。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：阅读输出[2]：'True\n'

要修复它，您可以：如果 read.rstrip() == 'True': 打印（"The line is True"）别的：打印（'The line is False'）

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

获取最后一行

从 .txt 文件中读取特定行

Reading specific line from .txt file

python

readline