我想在用户输入整数值而不是字符串值时生成异常..我该怎么办？

Question

def log_in():
    user_name1="xyz"
    try:
        user_name =(input("Enter your username:"))
        if (user_name ==user_name1):
            print("welcome")
    except TypeError:
        print("Enter only characters")
log_in()

我想在用户输入整数值而不是字符串值时生成异常

Answer 1

当您在控制台中输入整数时，input(...)将以字符串形式返回用户输入的输入。所以你永远不会得到TypeError例外。您也不需要在str()附近添加input()功能。

Answer 2

由于您对Type Checking感兴趣，您可能希望稍微颠倒您的逻辑：

def log_in():
    user_name1  = "xyz"
    user_name   = input("Enter your username:\n") # str()
    try:
        # FOR YOUR USE CASE, IT WOULD SUFFICE TO SIMPLY TRY TO CAST THE ENTERED 
        # INPUT TO AN INT (INITIALLY) -  REGARDLESS OF WHETHER IT'S INT OR STRING:
        # PERHAPS STRIP-OFF ALL EXTRA WHITE-SPACES AS WELL
        int( user_name.strip() )

        # IF WE ARE SURE IT'S AN INT, THEN: WE RESPOND ACCORDINGLY -
        print("Solely Numeric characters are not allowed as Username....")
        # THEN IMMEDIATELY BAIL OUT OF THE FUNCTION:
        return False
    except:
        pass

    # COMPARE ENTERED USERNAME WITH EXPECTED VALUE
    # IF ALL GOES WELL THEN, WELCOME THE USER
    if user_name.strip() == user_name1:
        print("welcome")
    else:
        print("Wrong Credentials....")

log_in()