How to Fix File Handling Issues in Python 3

问题

I'm trying to learn python 3. I was going through the exercises of File Handling. I'm having an issue with my code, when i try to write a file, it doesn't make any file sometimes and sometimes a file is generated but when i try to read it. It shows blank output. Most of time it give some sort of syntax error, while i'm using the basics and simple code. But sometime instead of using run in terminal, when i click on run code, it produces the output but still gives error on terminal.

I've tried doing it with, With and casual method. I've looked up on google for the issue but i didn't got any specific answer. I've tried to follow the python documentation and their code.

I've tried both open with method and casual method but i'm still facing this issue.

  ```
  with open('text.txt','w+')as f:
      f.write("Hell Men")
  with open('text.txt','r+')as f:
      print(f.read())
```

Also tried it this way:

file=open('word.txt','w')
file.write("Python you are making me mad")
file.read()

I was expecting the content of the file in output, but instead it shows blank on clicking run code.

Error: invalid syntax

回答1:

Hehe, its rather simple... whenever you open a file in a write format, you can only write to it, so to read it you need to close it and then reopen it as a read format.

example:

file=open("Example.txt","w")
file.write("Some text")
file.close()
file=open("Example.txt","r")
text=file.read()
print(text)
file.close()

回答2:

@Viswamedha Nalabotu Not necessary. you can read and write both. Yeah but using close is better as it can cause some problems. Thats why the with method was introduced. But as i mentioned before, there was a minor bug in VSC and a i got it how to do that.

you can read and write this way:

    f=open("note.txt",'w+')
    f.write("is it working still ?")
    f.seek(0)
    content=f.read()
    print (content)

回答3:

import sys
import os
import shutil

def leave():
    sys.exit("You are leaving CUI Text Editor")


def read():
    try:
        filename = input("Enter file name: ")
        target = open(filename, "r")
        readfile = target.read()
        print(readfile)
    except Exception as e:
        print("There was a problem: %s" % (e))


def delete():
    filename = input("Enter file name: ")
    try:
        os.unlink(filename)
    except Exception as e:
        print("There was a problem: %s" % (e))


def write():
    try:
        filename = input("Enter file name: ")
        target = open(filename, "a")
        while True:
            append = input()
            target.write(append)
            target.write("\n")
            if append.lower() == "menu":
                break
    except Exception as e:
        print("There was a problem: %s" % (e))


def cwd():
    try:
        print(os.getcwd())
        change = input("Change Y/N: ")
        if change.startswith("y"):
            path = input("New CWD: ")
            os.chdir(path)
    except Exception as e:
        print("There was a problem: %s" % (e))


def rename():
    try:
        filename = input("Enter current file name: ")
        new = input("Enter new file name: ")
        shutil.move(filename, new)
    except Exception as e:
        print("There was a problem: %s" % (e))


while True:
    print("Options: write, read, cwd, exit, delete, rename")
    do = input("So, what are you wishing for today: ")
    if do.lower() == "write":
        write()
    elif do.lower() == "read":
        read()
    elif do.lower() == "delete":
        delete()
    elif do.lower() == "exit":
        leave()
    elif do.lower() == "cwd":
        cwd()
    elif do.lower() == "rename":
        rename()

Have my advice, use r+ mode for safety, and use as many try catch blocks you wish to have. file management in python is easy then c++ streams.

回答4:

file=open('word.txt','rw+')
file.write("Python you are making me mad")
file.read()

回答5:

Okay, after searching and trying finally i got it. First of all it was a bug in Visual Studio code. You need to use exit() in terminal whenever such case occurs. Second you need to use seek(0) before printing, this way the simple program as i shared will run fine.

来源：https://stackoverflow.com/questions/56513739/how-to-fix-file-handling-issues-in-python-3

标签

python-3.x

file-handling