Question

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我知道很多人可能已经问过这个，但我已经看了几个解决其他人问题的方法，而且我尝试过的任何问题都没有用。我对编码很新，我必须为学校编写计算器代码。我有以下代码接受来自用户的数字输入：

num1 = float(input("Enter first number: "))
num2 = float(input("Enter second number: "))

当我输入一封信时，我收到以下错误消息：

追踪（最近一次通话）：文件“python”，第40行，in ValueError：无法将字符串转换为float：'d'

有人可以帮助我做到只接受号码吗？这是我的其余代码：

import time 

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

def subtract(x, y):
    return x - y

def multiply(x, y):
    return x * y

def divide(x, y):
    return x / y

def power(x, y):
    return x ** y

print("Welcome to the Calculator App!\n")
print("Select operation.\n")
print("1.Add")
print("2.Subtract")
print("3.Multiply")
print("4.Divide")
print("5.To the Power of\n")

choice = input("Enter choice(1, 2, 3, 4 or 5):")

while choice not in ("1","2","3","4","5"):
    print("Invalid Input")
    choice = input("Enter choice(1, 2, 3, 4 or 5):")

num1 = float(input("Enter first number: "))
num2 = float(input("Enter second number: "))    

while choice == '5' and num1 >= 1000000000:
    print("\nFirst number too high\n")
    num1 = float(input("Enter first number: "))
    num2 = float(input("Enter second number: "))

while choice == '5' and num2 >= 30:
    print("\nSecond number too high")
    num2 = float(input("Enter second number: "))

while choice == '4' and num2 == 0:
    print("\nCannot divide by zero")
    num2 = float(input("Enter second number: "))

if choice == '1':
    print(" ")
    print(num1,"+",num2,"=", add(num1,num2))

elif choice == '2':
    print(" ")
    print(num1,"-",num2,"=", subtract(num1,num2))

elif choice == '3':
    print(" ")
    print(num1,"*",num2,"=", multiply(num1,num2))

elif choice == '4':
    print(" ")
    print(num1,"/",num2,"=", divide(num1,num2))

elif choice == '5':
    print(" ")
    print(num1,"**",num2,"=", power(num1,num2))

else:
    print("\nInvalid input")

time.sleep(10)

这是我现在该部分的代码：

num1 = float(input("Enter first number: "))
while True:
    try:
        num1 = float(input("Enter first number: "))
    except ValueError:
        print("Please enter only a number")
        continue
    else:
    break

当我运行并故意输入字母g时，我收到以下错误消息：

Traceback (most recent call last):
    File "python", line 32 in <module>
ValueError: could not convert string to float: 'g'

如何使我的代码只接受数字（Python3）

0 个答案: