使用Python从文本文件中读取数据——第一行被跳过了

Question

我有一个名为test的文件，其内容如下：

a
b
c
d
e
f
g

我正在使用下面的python代码逐行读取文件并打印出来：

with open('test.txt') as x:
    for line in x:
        print(x.read())

这将会打印出文本文件的内容，除了第一行，即结果是:

b
c
d
e
f
g 

有没有人知道为什么文件的第一行会丢失？

- Riddle

Answer 1

因为for line in x会迭代每一行。

with open('test.txt') as x:
    for line in x:
        # By this point, line is set to the first line
        # the file cursor has advanced just past the first line
        print(x.read())
        # the above prints everything after the first line
        # file cursor reaches EOF, no more lines to iterate in for loop

也许您的意思是：

with open('test.txt') as x:
    print(x.read())

可以一次性打印全部内容，或者：

with open('test.txt') as x:
    for line in x:
        print line.rstrip()

逐行打印文件内容。建议采用后者，因为你不需要一次性将整个文件内容加载到内存中。

- jamylak