python3
1、算术运算：* 表示乘积运算。**表示乘方运算。print(2 * 5)print(2 ** 5)
2、*号常用在list变量前。表示解析出list中可迭代的元素，传递到函数中。fruits = ['lemon', 'pear', 'watermelon', 'tomato']print(fruits[0], fruits[1], fruits[2], fruits[3])print(*fruits)
*号的这种用法使得程序变得简便。fruits = ['lemon', 'pear', 'watermelon', 'tomato'](*fruits[1:], fruits[0])
3、*号常用在dict变量前。表示解析出dict中可迭代的values，传递到函数中。date_info = {'year': '2020', 'month': '01', 'day': '01'}track_info = {'artist': 'Beethoven', 'title': 'Symphony No 5'}filename = '{year}-{month}-{day}-{artist}-{title}.txt'.format( **date_info, **track_info)filename
4、*号用在函数中接收 keyword-only的参数def get_multiple(*keys, dictionary, default=None): return [ dictionary.get(key, default) for key in keys ]fruits = {'lemon': 'yellow', 'orange': 'orange', 'tomato': 'red'}get_multiple('lemon', 'tomato', 'squash', dictionary=fruits, default='unknown')
5、**用在函数中将参数打包成字典def tag(tag_name, **attributes): attribute_list = [ f'{name}='{value}'' for name, value in attributes.items() ] return f'<{tag_name} {' '.join(attribute_list)}>'print(tag('a', href='http://treyhunner.com'))print(tag('img', height=20, width=40, src='face.jpg'))