如果用戶輸入不是要求的字符串值的一部分，則默認為 output

Question

這是我剛才寫的一段代碼，我想讓它在默認情況下調用 add function，所以如果我只是輸入回車（或任何東西），它會問我我想添加哪兩個數字。 我試過把，

else:
num1 = float(input("Enter First Number: "))
num2 = float(input("Enter Second Number: "))
print(num1, "+", num2, "=", add(num1, num2))

但這是行不通的，任何幫助將不勝感激！ 這是下面的完整代碼

import math as m
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

def nroot(x, y):
    return x ** (1/y)

def sin(D):
    R = D / 180 * m.pi
    return(m.sin(R))
def cos(D):
    R = D / 180 * m.pi
    return(m.cos(R))

print("Select Operation.")
print("1. Add")
print("2. Subtract")
print("3. Multiply")
print("4. Divide")
print("5. Exponent")
print("6. sin(Degrees)")
print("7. cos(Degrees)")

while True:
    # Take input from user
    choice = input("Enter Choice[1-7]: ")

    #check if choice is one of the four
    if choice in ('1', '2', '3', '4', '5'):
        num1 = float(input("Enter First Number: "))
        num2 = float(input("Enter Second Number: "))

    if choice == '1':
        print(num1, "+", num2, "=", add(num1, num2))
    elif choice == '2':
        print(num1, "-", num2, "=", subtract(num1, num2))
    elif choice == '3':
        print(num1, "*", num2, "=", multiply(num1, num2))
    elif choice == '4':
        print(num1, "/", num2, "=", divide(num1, num2))
    elif choice == '5':
        print(num1, "^", num2, "=", power(num1, num2))

    if choice in('6','7'):
        angle = float(input('Enter Angle in degrees: '))

    if choice =='6':
        print('sin(',angle,') = ',sin(angle))
    elif choice =='7':
        print('cos(',angle,') = ',cos(angle))
  
    break

Answer 1

這對我來說很好-

import math as m
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

def nroot(x, y):
    return x ** (1/y)

def sin(D):
    R = D / 180 * m.pi
    return(m.sin(R))
def cos(D):
    R = D / 180 * m.pi
    return(m.cos(R))

print("Select Operation.")
print("1. Add")
print("2. Subtract")
print("3. Multiply")
print("4. Divide")
print("5. Exponent")
print("6. sin(Degrees)")
print("7. cos(Degrees)")

while True:
    # Take input from user
    choice = input("Enter Choice[1-7]: ")

    #check if choice is one of the four
    if choice in ('1', '2', '3', '4', '5'):
        num1 = float(input("Enter First Number: "))
        num2 = float(input("Enter Second Number: "))
    # Update:
    else:
        num1 = float(input("Enter First Number: "))
        num2 = float(input("Enter Second Number: "))
        print(num1, "+", num2, "=", add(num1, num2))

    if choice == '1':
        print(num1, "+", num2, "=", add(num1, num2))
    elif choice == '2':
        print(num1, "-", num2, "=", subtract(num1, num2))
    elif choice == '3':
        print(num1, "*", num2, "=", multiply(num1, num2))
    elif choice == '4':
        print(num1, "/", num2, "=", divide(num1, num2))
    elif choice == '5':
        print(num1, "^", num2, "=", power(num1, num2))

    if choice in('6','7'):
        angle = float(input('Enter Angle in degrees: '))

    if choice =='6':
        print('sin(',angle,') = ',sin(angle))
    elif choice =='7':
        print('cos(',angle,') = ',cos(angle))
  
    break