如何在 if 循环中中断代码？

Question

好的两个问题，我的导师希望我在 else 语句之后破坏我的代码，因为 menu() 函数在 "customer not found" 之后不断重复，但我不明白她的意思也出于某种原因我的代码仅使用 "customers" 列表中的第一个名字而不是所有名字运行，如果有人能指出我代码中的缺陷，那将非常感谢。

#Program 3 BankApp

def customerind(customer):
    ind = ""
    for i in range(len(customers)):
        if customer == customers[i]:
            ind = i
        if ind != "":
            return ind
        else:
            print("customer not found")

def printbalance(index):
    print("your remaining balance is", balances[index])
def menu():
    print("type D to deposit money", customer)
    print("type W to withdraw money", customer)
    print("type B to display balance", customer)
    print("type C to change user", customer)
    print("type E to exit", customer)
def withdraw(index, withdrawAmt):
    if withdrawAmt < balances[index]:
        balances[index] = balances[index] - withdrawAmt
    else:
        print("you went over your balance")
def deposit(index, depositAmt):
        balances[index] = balances[index] + depositAmt















global customers
customers= ["Mike", "Jane", "Steve"]
global balances
balances= [300, 300, 300]
global index
customer= input("what is your name?")
index= customerind(customer)
printbalance(index)


answer= ""
while answer != "E":
    menu()
    answer= input("what is your menu choice?")
    if answer=="C":
        customer= input("who are you?")
        index= customerind(customer)
    if answer== "W":
        withdrawAmt = float(input("how much did you want to withdraw today?"))
        withdraw(index, withdrawAmt)
        printbalance(index)
    if answer=="B":
        printbalance(index)
    if answer=="D":
        depositAmt = float(input("how much did you want to deposit today?"))
        deposit(index, depositAmt)
        printbalance(index)

Answer 1

你这里有一些问题。

1. "for some reason my code only runs using only the first name in the "客户列表

在您的 customerind 函数中，您仅在第一次迭代后打印 "customer not found"。您需要将 else 语句移到 for 循环之外，以便它可以遍历所有名称。

def customerind(customer):
  #Iterate through each name, and see if there is a match.
  for i in range(len(customers)):
    if customer == customers[i]:
      return i #If we found the name, instantly return the index. 
  #Outside of the for loop, will get called once above finishes iterating through all names.
  return -1 #Return -1 if no match, since the index can be any value 0 -> Infinity

所以这个函数现在的工作方式是，如果在 for 循环中找到名称，那么它 return 就是索引。如果遍历所有名称后仍未找到该名称，则该函数将 return -1。

既然这个函数设置好了一点，让我们看看底部的主要代码...

只要用户不键入 E，

menu() 就会不断被调用。那么如果你想在没有找到客户的情况下自动退出，你应该这样做：

answer= ""
while answer != "E":
    menu()
    answer= input("what is your menu choice?")
    if answer=="C":
        customer= input("who are you?")
        index= customerind(customer)
        if index == -1:
          print('Customer not found. Exiting...')
          break #Break out of the while loop above so the program exits. 
    if answer== "W":
        withdrawAmt = float(input("how much did you want to withdraw today?"))
        withdraw(index, withdrawAmt)
        printbalance(index)
    if answer=="B":
        printbalance(index)
    if answer=="D":
        depositAmt = float(input("how much did you want to deposit today?"))
        deposit(index, depositAmt)
        printbalance(index)

如何在 if 循环中中断代码？

how do you break code in a if loop?

python-3.3