python - 为什么我的 python 循环不断地遇到异常子句？

Question

classname = ""
classpick = input("Enter class name (\"A,B,C\") ")
while classname == "":
    try:
        if classpick.upper() == "A":
            classname = "classA.txt"
        elif classpick.upper() == "B":
            classname = "classB.txt"
        elif classpick.upper() == "C":
            classname = "classC.txt"
        elif classpick.upper() not in ["A","B","C"]:
            raise ValueError
        else:
            raise ValueError
    except ValueError:
        print("Invalid value. Please enter a letter A,B or C.")

这段代码对吗？由于某种原因，如果输入了无效的输入，代码将继续循环 except 子句。有什么想法吗？

Answer 1

您需要获取代码才能再次请求输入...尝试以下操作:

classname = ""
classpick = input("Enter class name (\"A,B,C\") ")
while classname == "":
    try:
        if classpick.upper() == "A":
            classname = "classA.txt"
        elif classpick.upper() == "B":
            classname = "classB.txt"
        elif classpick.upper() == "C":
            classname = "classC.txt"
        elif classpick.upper() not in ["A","B","C"]:
            raise ValueError
    except ValueError:
        print("Invalid value. Please enter a letter A,B or C.")
        classpick = input("Enter class name (\"A,B,C\") ")

编辑:

What is the last elif good for? – Jasper

没什么!感谢您的帮助!