Python如何传递任意数量的实参

传递任意数量的实参

形参前加一个 * ，Python会创建一个已形参为名的空元组，将所有收到的值都放到这个元组中：

def make_pizza(*toppings):
    print("\nMaking a pizza with the following toppings: ")
    for topping in toppings:
        print("- " + topping)
make_pizza('pepperoni')
make_pizza('mushroom', 'green peppers', 'extra cheese')

不管函数收到多少实参，这种语法都管用。

1. 结合使用位置实参和任意数量实参

def make_pizza(size, *toppings):
    print("\nMaking a " + str(size) + "-inch pizza with the following toppings: ")
    for topping in toppings:
        print("- " + topping)
make_pizza(16, 'pepperoni')
make_pizza(12, 'mushroom', 'green peppers', 'extra cheese')

运行结果：

Making a 16-inch pizza with the following toppings: 
- pepperoni
Making a 12-inch pizza with the following toppings: 
- mushroom
- green peppers
- extra cheese

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2. 使用任意数量的关键字实参

def build_profile(first, last, **user_info):
    profile = dict()
    profile['first_name'] = first
    profile['last_name'] = last
    for key, value in user_info.items():
        profile[key] = value
    return profile
user_profile = build_profile('albert', 'einstein', location='princeton', field='physic')
print(user_profile)

形参**user_info中的两个星号让python创建了一个名为user_info的空字典。