AttributeError：“ _ io.TextIOWrapper”对象没有属性“ next” python

Question

我正在使用python 3.3.3。我正在从tutorialspoint.com做本教程。我无法理解此错误是什么。

这是我的代码：

fo = open("foo.txt", "w")
print ("Name of the file: ", fo.name)

# Assuming file has following 5 lines
# This is 1st line
# This is 2nd line
# This is 3rd line
# This is 4th line
# This is 5th line

seq = ["This is 6th line\n", "This is 7th line"]
# Write sequence of lines at the end of the file.
fo.seek(0, 2)
line = fo.writelines( seq )

# Now read complete file from beginning.
fo.seek(0,0)
for index in range(7):
 #  line = fo.next()
   print ("Line No %d - %s" % (index, line)+"\n")

# Close opend file
fo.close()

错误：

Name of the file:  foo.txt
Traceback (most recent call last):
  File "C:/Users/DELL/Desktop/python/s/fyp/filewrite.py", line 19, in <module>
    line = fo.next()
AttributeError: '_io.TextIOWrapper' object has no attribute 'next'

Answer 1

您在这里遇到问题有两个原因。第一个是您fo以只写模式创建的。您需要一个可以读写的文件对象。您还可以使用with关键字在完成处理后自动销毁文件对象，而不必担心手动关闭它：

# the plus sign means "and write also"
with open("foo.txt", "r+") as fo:
    # do write operations here
    # do read operations here

第二个是（就像您非常强烈地指出的错误一样）文件对象fo（文本文件对象）没有next方法。您正在使用针对Python
2.x编写的教程，但您正在使用Python3.x。这对您来说并不顺利。（我相信nextwas /也许在Python
2.x中有效，但在3.x中无效。）相反，与nextPython 3.x最类似的是readline，如下所示：

for index in range(7):
    line = fo.readline()
    print("Line No %d - %s % (index, line) + "\n")

请注意，这仅在文件至少有7行时有效。否则，您将遇到异常。一个遍历文本文件的更安全，更简单的方法是使用for循环：

index = 0
for line in file:
    print("Line No %d - %s % (index, line) + "\n")
    index += 1

或者，如果您想获得更多的pythonic，可以使用enumerate函数：

for index, line in enumerate(file):
    print("Line No %d - %s % (index, line) + "\n")