标签：style blog color 使用 strong ar art div 代码
函数：
定义函数
#area.py from math import pi def area(radius): """Return the area of a circle with the given radius.""" return pi * radius ** 2
>>> ================================ RESTART ================================ >>> >>> area(5.5) 95.03317777109125 >>> print(area.__doc__) Return the area of a circle with the given radius. >>>
doctest #可用于自动运行文档字符串中的python示例代码
全局变量访问时一定要加上global
#error name = ‘Jack‘ def say_hello(): print(‘Hello ‘ + name + ‘!‘) def change_name(new_name): name = new_name
>>> say_hello() Hello Jack! >>> change_name(‘Mary‘) >>> say_hello() Hello Jack!
#correct name = ‘Jack‘ def say_hello(): print(‘Hello ‘ + name + ‘!‘) def change_name(new_name): global name name = new_name
>>> say_hello() Hello Jack! >>> change_name(‘Mary‘) >>> say_hello() Hello Mary!
main():被认为是程序的起点，可选不一定要。运行时必须输入main()
python中参数的传递都是按引用传参，python不支持按值传参
在引用传参中，无法修改参数的值。下面的函数不起作用：
#reference.py def set1(x): x = 1
>>> ================================ RESTART ================================ >>> >>> y = 5 >>> set1(y) >>> y 5
函数参数默认值：
注意：包含默认参数的形参一定要放在无默认参数的形参后面
只有第一次调用函数时给默认参数赋值！ #还不理解，先记下来
#greetings.py def greet(name, greeting = ‘Hello‘): print(greeting, name + ‘!‘)
>>> greet(‘bob‘) Hello bob! >>> greet(‘bob‘, ‘Good morning‘) Good morning bob!
使用关键字传参，即在使用时也指明形参，可以不理会顺序，很好用：
#greetings.py def greet(name = ‘Bob‘, greeting = ‘Hello‘): print(greeting, name + ‘!‘)
>>> greet(greeting = ‘Good evening‘, name = ‘Mary‘) Good evening Mary! >>> greet(greeting = ‘Good evening‘) Good evening Bob!
也可以用模块化的方式来调用，模块中不包括main函数
>>> import greetings >>> greetings.greet() Hello Bob! >>> dir(greetings) [‘__builtins__‘, ‘__cached__‘, ‘__doc__‘, ‘__file__‘, ‘__loader__‘, ‘__name__‘, ‘__package__‘, ‘__spec__‘, ‘greet‘]
标签：style blog color 使用 strong ar art div 代码
原文地址：http://www.cnblogs.com/dplearning/p/3951490.html
