Try/Except 错误处理无法识别 ValueError

Question

在以下脚本中：

# shows multiplication table of a number upto that number

import time

while True:

    num = input("Enter number: ")

    try:

        def mult():

            for i in range(1, int(num)+1):

                print(str(i) + " x " + num + " = " + str(i * int(num)))

    except ValueError:

        print("Please enter a number")

        continue

    mult()

    time.sleep(2)

如果输入的不是整数值，我希望显示“请输入数字” ，因为在内部找到了。numValueErrorint(num)mult()

但是，try/except 块似乎不起作用，因为在输入非数字字符串时，它会显示 Python 的 Traceback 错误：

Enter number: forty five

Traceback (most recent call last):

  File "...", line 13, in <module>

    mult()

  File "...", line 7, in mult

    for i in range(1, int(num)+1):

ValueError: invalid literal for int() with base 10: 'forty five'

为什么错误处理不起作用？

Answer 1

您可以删除 mult() 函数定义，因为它似乎不是特别重要（如果重要请纠正我）。您的代码将如下所示：import timewhile True:&nbsp; &nbsp; num = input("Enter number: ")&nbsp; &nbsp; try:&nbsp; &nbsp; &nbsp; &nbsp; for i in range(1, int(num)+1):&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; print(str(i) + " x " + num + " = " + str(i * int(num)))&nbsp; &nbsp; except ValueError:&nbsp; &nbsp; &nbsp; &nbsp; print("Please enter a number")&nbsp; &nbsp; &nbsp; &nbsp; continue&nbsp; &nbsp; time.sleep(2)这最初不起作用的原因是因为您的 try 语句围绕着一个定义，而不是围绕着 mult() 函数的实际调用。这意味着当它运行时，它试图定义一个名为 的函数mult，并且运行良好。然而，当它真正调用第 13 行的函数时，由于没有 try 语句而导致它中断。

Answer 2

为什么要在 try 中定义 mult？尝试将 try 放入函数中。现在您正在尝试检查是否可以创建函数 mult。成功后你尝试调用它（你会遇到问题的地方）。`# shows multiplication table of a number upto that numberimport timewhile True:&nbsp; &nbsp; num = input("Enter number: ")&nbsp; &nbsp; def mult():&nbsp; &nbsp; &nbsp; &nbsp; try:&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; for i in range(1, int(num)+1):&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; print(str(i) + " x " + num + " = " + str(i * int(num)))&nbsp; &nbsp; &nbsp; &nbsp; except ValueError:&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; print("Please enter a number")&nbsp; &nbsp; &nbsp; &nbsp; &nbsp; &nbsp; continuemult()time.sleep(2)`这应该有效，另外请注意，如果你想在你的函数中输入一个值，应该这样做：def mult(data)调用：mult('数据')