Python 函数传递任意数量的实参

函数传递任意数量的实参

• *形参名，形参名中的星号让python创建了一个空元组，并将收到的所有值都封装到这个元组中

# 案例 *toppings 形参名中的星号让python创建了一个空元组，并将收到的所有值都封装到这个元组中
def make_pizza(*toppings):
    '''打印顾客点的所有配料'''
    print(toppings)

make_pizza('pepperoni')
make_pizza('mushrooms','green peopers','extra cheese')

('pepperoni',)
('mushrooms', 'green peopers', 'extra cheese')

def make_pizza(*toppings):
    """概述要做的比萨"""
    print("\nMaking a pizza with the following toppings: ")
    for topping in toppings:
        print("- " + topping)
make_pizza('pepperoni')
make_pizza('mushrooms','green peppers','extra cheese')

Making a pizza with the following toppings:
- pepperoni

Making a pizza with the following toppings:
- mushrooms
- green peppers
- extra cheese

结合使用位置实参和任意数量实参

• 让函数接收不同类型的实参，必须在函数定义中将接纳任意数量实参的形参放在最后，python先匹配位置实参和关键字实参，再将余下的实参都收集到最后一个形参中

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,'mushrooms','green peppers','extra cheese')

Making a 16-inch pizza with the following toppings:
- pepperoni

Making a 12-inch pizza with the following toppings:
- mushrooms
- green peppers
- extra cheese

使用任意数量的关键字实参

• 两个星号创建了一个空字典，将收到的所有名称-值对都封装到这个字典中

# 案例
def build_profile(first,last, **user_info):
    '''创建一个字典，其中包含我们知道的有关用户的一切'''
    profile = {}
    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 = 'physics')
print(user_profile)

{'first_name': 'albert', 'last_name': 'einstein', 'location': 'princeton', 'field': 'physics'}

练习

# 1.三明治
# 编写一个函数，它接受顾客要在三明治中添加的一系列食材。这个函数只有一个形参（它收集函数调用中提供的所有食材），并打印一条消息，对顾客
# 点的三明治进行概述。调用这个函数三次，每次都提供不同数量的实参
def add_sandwich(*foods):
    print("\n I'll make you a great sandwich: ")
    for food in foods:
        print("....adding " + food + " to your sandwich.")
    print("Your sandwich is ready!")

add_sandwich('roast beef', 'cheddar cheese', 'lettuce', 'honey dijon')
add_sandwich('turkey', 'apple slices', 'honey mustard')
add_sandwich('peanut butter', 'strawberry jam')

 I'll make you a great sandwich:
....adding roast beef to your sandwich.
....adding cheddar cheese to your sandwich.
....adding lettuce to your sandwich.
....adding honey dijon to your sandwich.
Your sandwich is ready!

 I'll make you a great sandwich:
....adding turkey to your sandwich.
....adding apple slices to your sandwich.
....adding honey mustard to your sandwich.
Your sandwich is ready!

 I'll make you a great sandwich:
....adding peanut butter to your sandwich.
....adding strawberry jam to your sandwich.
Your sandwich is ready!

# 2.用户简介
# 在其中调用 build_profile() 来创建有关你的简介；调用这个函数时，指定你的名和姓，以及三个描述你的键 - 值对。
def build_profile(first,last, **user_info):
    '''创建一个字典，其中包含我们知道的有关用户的一切'''
    profile = {}
    profile['first_name'] = first
    profile['last_name'] = last
    for key,value in user_info.items():
        profile[key] = value
    return profile
user_profile = build_profile('li','yege',
                            height = '170cm',
                            weight = '70kg',
                            hobby = 'basketball',
                            )
print(user_profile)

{'first_name': 'li', 'last_name': 'yege', 'height': '170cm', 'weight': '70kg', 'hobby': 'basketball'}

# 3.汽车
# 编写一个函数，将一辆汽车的信息存储在一个字典中。这个函数总是接受制造商和型号，还接受任意数量的关键字实参。这样调用这个函数：提供必不可
# 少的信息，以及两个名称 — 值对，如颜色和选装配件。这个函数必须能够像下面这样进行调用
def build_cars(made_address, model, **user_info):
    cars = {}
    cars['address'] = made_address
    cars['model'] = model
    for key,value in user_info.items():
        cars[key] = value
    print(cars)
build_cars('china', 'big',color = 'blue', name = 'changcheng')

{'address': 'china', 'model': 'big', 'color': 'blue', 'name': 'changcheng'}