Question

每当我测试我的计算器以查看它如何处理非数字的输入时，它会标记一个ValueError。更准确地说，这个＆＃34; ValueError：无法将字符串转换为浮点数：＆＃39; a＆＃39;＆＃34;＆＃39;＆＃39;＆＃39;我试图修改这个，所以有一个处理非整数的解决方案但无济于事...非常感谢帮助。

到目前为止，这是我的代码：

print("1. ADDITION ")
print("2. MULTIPLICATION ")
print("3. TAKEAWAY ")
print("4. DIVISION ")

Operator = int(input("please enter one of the numbers above to decide the operator you want. "))

while Operator > 4:
    print("Please select a number from the options above. ")
    Operator = int(input("please enter one of the numbers above to decide the operator you want. "))
    if Operator != (1 or 2 or 3 or 4):
        print("please enter one of the options above. ")
        Operator = int(input("please enter one of the numbers above to decide the operator you want. "))
    continue

while True:
    Num1 = float(input("Please enter first number. "))
    if Num1 == float(Num1):
        print("thanks! ")
    elif Num1 != float(Num1):
        Num1 = float(input("Please enter first number. "))
    break

while True:
    Num2 = float(input("Please enter second number. "))
    if Num2 == float(Num2):
        print("thanks ")
    elif Num1 != float(Num1):
        Num1 = float(input("Please enter first number. "))
    break

Answer 1

您正在寻找异常处理。像这样的Smthng：

input = 'a'
try:
    int(a)
except ValueError:
    print 'Input is not integer'

Answer 2

请阅读处理例外情况的文档：

https://docs.python.org/2/tutorial/errors.html#handling-exceptions

表示浮动：

try:
    x = float(input("Please enter a number: "))
    break
except ValueError:
    print "Oops!  That was no valid number.  Try again..."

Answer 3

注意：您应根据PEP8将变量命名为小写，请参阅：What is the naming convention in Python for variable and function names?。

如果您想要在没有ValueError之前重试输入，请将其置于循环中：

print("Please select a number from the options above.")
while True:
    try:
        operator = int(input("please enter one of the numbers above to decide the operator you want: "))
    except ValueError:
        print("Sorry, not a number. Please retry.")
    else:
        if 1 <= operator <= 4:
            break
        else:
            print("Sorry, choose a value between 1 and 4.")

注意：在Python 3.x中使用input或在Python 2.7中使用raw_input

1. ADDITION
2. MULTIPLICATION
3. TAKEAWAY
4. DIVISION
Please select a number from the options above.
please enter one of the numbers above to decide the operator you want: spam
Sorry, not a number. Please retry.
please enter one of the numbers above to decide the operator you want: 12
Sorry, choose a value between 1 and 4.
please enter one of the numbers above to decide the operator you want: 2

我的初学python项目（计算器）输入有问题

3 个答案: