Python - 为什么我的.read（）不能用于我的.txt文件？没有输出到cmd线

Question

运行

我正在运行Python版本3.5，来自Windows 7上的cmd提示

.txt文件中的内容以及cmd输出的内容

What the cmd prompt outputs

What the .txt contains

我当前的代码

"""Opens a file and let\'s you read it and write to it"""

open_pls = open("text.txt", "a+")

#Main function
def read_write():
    program_running = True
    while program_running == True:
        choice = input("Write R for read, write W for write or write X for exit:")
        choice = choice.upper()
        if choice == "W":
            what_write = input("What do you want to write to the end of the file?:")
            open_pls.write(what_write)
            print("Succesfully written!")
            print("Running program again...")
            continue
        elif choice == "R":
            print("This file contains:")
            read_pls = open_pls.read()
            print(read_pls)
            print("Running program again...")
            continue
        elif choice == "X":
            program_running = False
            open_pls.close()
        else:
            print("That was not a valid command!")
            print("Running program again...")
            continue

run = input("Run the program? (Y/N):")
run = run.upper()
if run == "Y":
    read_write()
elif run == "N":
    input("Exit program? Press enter:")
else:
    input("Exit program? Press enter:")

我认为问题出在这里

    elif choice == "R":
        print("This file contains:")
        read_pls = open_pls.read()
        print(read_pls)
        print("Running program again...")
        continue

Answer 1

当您使用'a'模式打开文件时，文件将搜索到最后。要获取文件的内容，您必须回头查看：open_pls.seek(0)。

Answer 2

当您使用'a'追加模式打开文件时，操作系统会为您提供一个文件位于文件末尾的文件。

你可以先尝试回到起点，但这取决于你的操作系统是否真的被允许：

open_pls.seek(0)
read_pls = open_pls.read()

您可能希望以'r+'模式打开文件，并在撰写时寻求结束。