《笨办法学Python 3》练习20报错：str对象无'read'属性，如何解决？

错误原因 #

你在调用print_all("Let's print three lines:")时犯了个简单错误：print_all函数设计用来接收文件对象，并调用它的read()方法，但你传了一个字符串进去。字符串类型没有read()属性，所以抛出这个错误。

修复方案 #

把这行错误的调用改成直接打印提示文本就行——这行本来就是输出一句话，不需要调用读取文件的函数。同时修正原代码里的小笔误（"tapea"改成"tape"），修复后的完整代码如下：

from sys import argv
from os.path import *

script, input_file = argv


def print_all(f):
    print(f.read())


def rewind(f):
    f.seek(0)


def print_a_line(line_count, f):
    print(line_count, f.readline())


current_file = open(input_file)

print("First let's print the whole file:\n")

print_all(current_file)

print("Now let's rewind, kind of like a tape.")

rewind(current_file)

# 修改点：直接打印提示文本，无需传给print_all函数
print("Let's print three lines:")

current_line = 1
print_a_line(current_line, current_file)

current_line = current_line + 1
print_a_line(current_line, current_file)

current_line = current_line + 1
print_a_line(current_line, current_file)

验证输出 #

运行修复后的代码，就能得到你期望的结果：

$ python ex20.py test.txt
First let's print the whole file:

This is line 1
This is line 2
This line 3

Now let's rewind, kind of like a tape.
Let's print three lines:
1 This is line 1

2 This  is line 2 

3 This is line 3

内容的提问来源于stack exchange，提问作者Rayan Mahmood Chaudhry