在处理可能引发异常的输入时,如何使用while循环?

您只需创建一个while循环,并在找到文件时中断。所以应该是这样的:

if user_choice == commands[2]: 
    while True:
        try:
            file_name = input("Enter file name: ")
            print(INPUT(file_name))
            #if the file is found (if statement) (I don't know how you would do this as i haven't seen the full code):
                break

        except FileNotFoundError:
            print("The file name you entered does not exist.")
            file_name = input("Enter file name: ")

试试这样:

if user_choice == commands[2]: 

var = 0
while var != 1 :
  try:
        file_name = input("Enter file name: ")
        print(INPUT(file_name))
        var = 1

    except FileNotFoundError:
        print("The file name you entered does not exist.")
        file_name = input("Enter file name: ")