Python：輸入接受整數但在字符串上崩潰

Question

對於我的作業中的練習問題，我正在制作一個猜測游戲，首先要求一個數字。 我正在嘗試實現一種在給定字符串時打印“無效輸入”的方法，但是我收到錯誤消息。 這是我的代碼：

def get_input():
    '''
    Continually prompt the user for a number, 1,2 or 3 until
    the user provides a good input. You will need a type conversion.
    :return: The users chosen number as an integer
    '''
    guess=int(input("give me 1,2,3"))
    while True:
        if guess==1 or guess==2 or guess==3:
            return guess
        else:
            print "Invalid input!"

        guess=int(input("give me 1,2,3"))

當我輸入諸如的字符串時，我收到此消息

hello/System/Library/Frameworks/Python.framework/Versions/2.6/bin/python2.6 /Users/bob/PycharmProjects/untitled/warmup/__init__.py

給我1,2,3hello

Traceback (most recent call last):
  File "/Users/bob/PycharmProjects/untitled/warmup/__init__.py", line 51, in <module>
    get_input()
  File "/Users/bob/PycharmProjects/untitled/warmup/__init__.py", line 43, in get_input
    guess=int(input("give me 1,2,3"))
  File "<string>", line 1, in <module>
NameError: name 'hello' is not defined

Process finished with exit code 1

Answer 1

你需要對python2使用raw_input ，輸入嘗試評估字符串，以便它查找名為name和errors的變量，因為在任何地方都沒有名為name變量。 你永遠不應該在python2中使用input ，它等同於具有明顯安全風險的eval(raw_input()) 。

因此，為了更清楚地拼寫它， 不要使用輸入從python2中的用戶獲取輸入，使用raw_input() ，在您的情況下使用try/except捕獲ValueError try/except的raw_input 。

def get_input():
    '''
    Continually prompt the user for a number, 1,2 or 3 until
    the user provides a good input. You will need a type conversion.
    :return: The users chosen number as an integer
    '''

    while True:
        try:
            guess = int(raw_input("give me 1,2,3"))
            if guess in (1, 2, 3):
                return guess
        except ValueError:
            pass
        print("Invalid input!")

您只需要為1,2或3進行檢查，這意味着您在確認后也可以進行投射：

def get_input():
    '''
    Continually prompt the user for a number, 1,2 or 3 until
    the user provides a good input. You will need a type conversion.
    :return: The users chosen number as an integer
    '''

    while True:
        guess = raw_input("give me 1,2,3")
        if guess in ("1", "2", "3"):
            return int(guess)
        print("Invalid input!")

Answer 2

您應該在轉換為int之前驗證輸入類型：

guess = raw_input("give me 1,2,3")

while True:
   if guess == '1' or guess == '2' or guess == '3':
      return int(guess)
   else:
      print "Invalid input!"

   guess = raw_input("give me 1,2,3")