Question

请问以下代码有什么问题吗？

def add(x, y):
   return x + y
while True:
    try:
        num1 = float(input('Enter first number: ')
    except:
        print ('num1 is a complex/string. Only Integers or Float is allowed. Please key in again')
    try:
        num2 = float(input("Enter first number: ")
    except:
        print ('num2 is a complex/string. Only Integers or Float is allowed. Please key in again')
    break
print(num1,"+",num2,"=", add(num1,num2))
input("Press enter to exit ;)")

Answer 1

（除了语法错误-缺少括号...）

break语句转义了while循环，因此将其放在迭代结束时，您将在第一次迭代时中断，因此如果输入无效的输入，则不会再询问它们，因为你会爆发的。

此外，就只有一个循环而言，逻辑是错误的。如果他们输入有效的num1，然后输入无效的num2，则将要求他们（如果您移动break）再次输入num1和num2 -而不是再次num2。

要解决这些问题，您可以对代码进行分隔-将输入逻辑移至函数：

def get_float(prompt):
    while True:
        try:
            return float(input(prompt))
            break
        except ValueError:
            print('sorry, invalid input')

然后您的主要代码更容易理解：

def add(x, y):
   return x + y

num1 = get_float('Enter first number: ')
num2 = get_float('Enter second number: ')
result = add(num1, num2)
print(num1, '+', num2, '=', result)
input('press enter to exit')

试运行显示出良好的效果：

Enter first number: one
sorry, invalid input
Enter first number: bob
sorry, invalid input
Enter first number: 20
Enter second number: nine
sorry, invalid input
Enter second number: 8.89
20.0 + 8.89 = 28.89
press enter to exit

Answer 2

您需要使用raw_input仅接受输入提示。

def add(x, y):
   return x + y
while True:
    try:
        num1 = float(raw_input('Enter first number: '))
    except:
        print ('num1 is a complex/string. Only Integers or Float is allowed. Please key in again')
    try:
        num2 = float(raw_input("Enter second number: "))
    except:
        print ('num2 is a complex/string. Only Integers or Float is allowed. Please key in again')
    break
print(num1,"+",num2,"=", add(num1,num2))

raw_input("Press enter to exit ;)")

Python，而“ True Condition”引发语法错误

2 个答案: