自定义函数(def):形参和实参
1.函数文档
>>> def say(name, words): '函数定义阶段, name, words叫形参' '传递进来 name words是实参' print(name + ' say: ' + words) >>> say('itxds', 'hello') itxds say: hello >>>
2.打印文档
>>> say('itxds', 'hello') itxds say: hello >>> say.__doc__ '函数定义阶段, name, words叫形参' >>> help(say) Help on function say in module __main__: say(name, words) 函数定义阶段, name, words叫形参 >>>
3.关键字参数
使用顺序参数时,如果函数的参数多达十几个甚至几十个,这样在调用的时候很容出错。
>>> def say(name, words): '函数定义阶段, name, words叫形参' '传递进来 name words是实参' print(name + ' say: ' + words) >>> say(words='hello', name='itxds') itxds say: hello >>>
4.默认参数
>>> def say(name = 'itxds', words = 'hello'): '函数定义阶段, name, words叫形参' '传递进来 name words是实参' print(name + ' say: ' + words) >>> say() itxds say: hello >>>
5.收集参数
在调用函数时,系统将收集参数以元组的形式传递给函数内部调用
>>> def say(*params): print(params) >>> say(1,3,4,5,6,7,8) (1, 3, 4, 5, 6, 7, 8) >>>
6.收集参数与关键字参数结合使用
>>> def say(*params, name='itxds'): print(name) print(params) >>> >>> say(1,2,4,5, name='zhangsna') zhangsna (1, 2, 4, 5) >>>