python拆包和封包

"""
python的拆包和封包之 *号在函数形参和实参的区别
1. 在函数形参定义时添加*就是封包过程，封包默认是以元组形式进行封包
2. 在函数实参调用过程添加*就是拆包过程，拆包过程中会报列表或者元组拆成单个元素
"""

subject = ["math", "chinese", 'english', 'physics', 'history']


def print_subject_one(sub):
    print(*sub)


def print_subject_two(*sub):
    print(sub)


def print_subject_three(*sub):
    print(*sub)


def print_subject_four(*sub):
    print(*sub)


def print_subject_five(*sub):
    print(sub)


print_subject_one(subject)  # math chinese english physics history
print_subject_two(subject)  # (['math', 'chinese', 'english', 'physics', 'history'],)
print_subject_three(subject)  # ['math', 'chinese', 'english', 'physics', 'history']
print_subject_four(*subject)  # math chinese english physics history
print_subject_five(*subject)  # ('math', 'chinese', 'english', 'physics', 'history')


"""
python的拆包和封包之 **号在函数形参和实参的区别
1. 在函数形参定义时添加**就是封包过程，封包默认是字典形式进行封包,
2. 在函数实参调用过程添加**就是拆包过程，通常在存在关键字参数的函数去使用**对字典进行拆包
"""

hobby = {"jack": "dance", "henry": "basketball", "jenny": "swimming", "richard": "reading"}


def print_hobby_one(**bby):
    print(bby)


def print_hobby_two(**bby):
    print(bby)


def print_hobby_three(**bby):
    if "jack" in bby:
        print('jack like dance')
    if "jenny" in bby:
        print("jenny like swimming")


print_hobby_one(**hobby)  # {'jack': 'dance', 'henry': 'basketball', 'jenny': 'swimming', 'richard': 'reading'}
print_hobby_two(jack='dance', henry='basketball')  # {'jack': 'dance', 'henry': 'basketball'}
print_hobby_three(**hobby)  # jack like dance  jenny like swimming


"""
python的拆包和封包之 * 在其它场景的应用
"""

a, *_, c = [1, 2, 3, 4, 5, 6]  # a=1, c=6
print(a)  # a=1, c=6
print(c)  # a=1, c=6


a, b, *_ = [1, 2, 3, 4, 5, 6]
print(a)  # a=1
print(b)  # b=2


# 一行代码搞定两个变量交换赋值
x = 10
y = 20

x, y = y, x
print(x)  # x = 20
print(y)  # y = 10