python - print(f.read()) io.UnsupportedOperation: 不可读

Question

import os

path = os.getcwd()
print(path)
filename = "aboutPython.txt"
file = path + '\\' + filename
print(file)

# open a local txt file for append
f = open(file, "a")

# read the entire file
print(f.read())

# read the first 250 characters
print(f.read(5))

# read one line
print(f.readline())

# you can append because of how the file was opened  
f.write("Now the file has one more line!")
print(f.read())

此代码引发此错误：

Traceback (most recent call last):
  File "C:/Users/wrk/weemos/append_file.py", line 14, in <module>
    print(f.read())
io.UnsupportedOperation: not readable

标签： python

Answer 1

首先以读取模式打开文件r以读取它：

f = open(file, "r")
# read the entire file
print(f.read())

# read the first 250 characters
f.seek(0)
print(f.read(5))

# read one line
f.seek(0)
print(f.readline())
f.close()

现在，再次以追加a模式打开它以追加，然后r再次以读取模式打开它，因为您稍后也会从中读取：

f = open(file, "a")
# you can append because of how the file was opened  
f.write("Now the file has one more line!")
f.close()
f = open(file, "r")
print(f.read())
f.close()