python
spyder
在python中常常使用def关键字来定义一个函数 。注意缩进。举个例子：def sign(x): if x > 0: return 'positive' elif x < 0: return 'negative' else: return 'zero'for x in [-1, 0, 1]: print(sign(x))# Prints 'negative', 'zero', 'positive'
输出结果如下 :negativezeropositive
在定义函数的时候我们也可以缺省一些参数。举个例子：def hello(name, loud=False): if loud: print('HELLO, %s!' % name.upper()) else: print('Hello, %s' % name)hello('Bob') # Prints 'Hello, Bob'hello('Fred', loud=True) # Prints 'HELLO, FRED!'
运行结果如下：Hello, BobHELLO, FRED!
python定义类的方式也非常直接。class Greeter(object): # Constructor def __init__(self, name): self.name = name # Create an instance variable # Instance method def greet(self, loud=False): if loud: print('HELLO, %s!' % self.name.upper()) else: print('Hello, %s' % self.name)g = Greeter('Fred') # Construct an instance of the Greeter classg.greet() # Call an instance method; prints 'Hello, Fred'g.greet(loud=True) # Call an instance method; prints 'HELLO, FRED!'
运行结果如下：Hello, FredHELLO, FRED!