Python 我怎么回圈

我已经在网上尝试和阅读了2个多小时，但没有成功。请帮忙！如何以不固定的次数循环回代码第6行（见下文）？我知道这与while循环有关，但我真的不确定。该代码是为某人借出一定数量的一本书而设计的，但我不知道如何允许他们借出多本书。如果可能的话，请帮忙。我知道这个网站不是用来分配任务的，但我在这里真的很挣扎，如果我能得到帮助，我会知道未来。这是我的代码，不是很准确，但我是一个学习的学生

task=input("Enter 'b' to borrow a book, press 'x' to exit. \n")
if task.lower()== "b":
    myfile=open("books.txt", "r+") 
    details=myfile.readlines() 
    while True:
        book=input("Enter the 8 digit book code. \n")
        if len(book) !=8 
            print("Your code is not 8 digits long, please try again.\n") 
        else:
            break 
        f = open("books.txt", "r+") #I have a file with all the books, their codes and prices
        for line in f.readlines():
            quantity=input("How many copies of the book do you wish to purchase?\n")
            t = line.split(" ")
            price = float(t[3])
            code = t[1]
            NameOfBook = t[2]
            total=(price)* int(quantity)
        # Ask them if they'd like to purchase more books, if so I would like to then direct them back to  "book=input("Enter the 8 digit book code. \n")"

            print ("Your receipt is:",digits,"," ,name, name2) #How can I repeat this for however many books they'd like to purchase?
            print ("Your total is £",total) #Then add the total cost of everything together and print it

---

散列显示了我希望发生的事情。提前感谢，我很抱歉让人讨厌

您可以将for循环代码放在else语句下，然后在末尾添加另一个语句，询问用户是否要完成另一个事务。如果是，请继续，否则请中断。以下是您可以做的：

task=input("Enter 'b' to borrow a book, press 'x' to exit. \n")
if task.lower()== "b":
     myfile=open("books.txt", "r+") 
     details=myfile.readlines() 
     while True:
          book=input("Enter the 8 digit book code. \n")
          if len(book) !=8 
                print("Your code is not 8 digits long, please
               try again.\n") 
          else:

               f = open("books.txt", "r+") 
               for line in f.readlines():
                     quantity=input("How many copies of the book do   
                    you wish to purchase?\n")
                     t = line.split(" ")
                     price = float(t[3])
                     code = t[1]
                     NameOfBook = t[2]
                     total=(price)* int(quantity)
                     print ("Your receipt is:",digits,"," ,name,  
                      name2) 
                     print ("Your total is £",total)
               answer = input("Do you want to enter another book?")
               if answer == "yes":
                    continue
               else:
                    break

---

将第11行（最后2行除外）的所有内容缩进另一个级别，使其位于

while

块内。Python是布局敏感的，缩进指示块。好的就可以了。。。。。