python - 在 Python 中，我的函数不返回值

Question

当我运行该程序时，它没有返回输入的值，即 num1 和 num2。

有人可以告诉我我做错了什么吗？

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

print('Lists of operations: ')
print('1. add')
print('2. subtract')
print('3. multiply')
print('4. divide')

operations = int(input('Select an operation (1/2/3/4): '))

num1 = float(input('Enter a number: '))
num2 = float(input('Enter a number: '))
# Functions aren't returning values
if '1' == operations:
    print(num1,'+',num2,'equals'+ add(num1, num2))
# Functions aren't returning values
elif '2' == operations:
    print(num1,'-',num2,'equals', subtract(num1, num2))
# Functions aren't returning values
elif '3' == operations:
    print(num1,'*',num2,'equals', multiply(num1, num2))
# Functions aren't returning values
elif '4' == operations:
    print(num1,'/',num2,'equals', divide(num1, num2))

Answer 1

您正在将整数与字符串进行比较:

if '1' == operations:

使用1代替'1'，其他数字也是如此:

if 1 == operations: