实现一个计算器，可以实现+ – * / 运算

num1 = float(input(“请输入第一个数：”))
operator = input(“请输入运算符(+, -, *, /)：”)
num2 = float(input(“请输入第二个数：”))

match operator:
case “+”:
print(num1 + num2)
case “-“:
print(num1 – num2)
case “*”:
print(num1 * num2)
case “/”:
if num2 != 0:
print(num1 / num2)
else:
print(“除数不能为0”)
case _:
print(“输入错误，请输入正确的运算符”)