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function.py
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107 lines (79 loc) · 2.22 KB
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#!/usr/bin/python
#coding:utf-8
def sayHi():
print 'hi';
sayHi();
# 只有在形参表末尾的那些参数可以有默认参数值，
# 即你不能在声明函数形参的时候，
# 先声明有默认值的形参而后声明没有默认值的形参。
def greet(name, word = 'hi'): # word is optional
print word + ',' + name;
greet('joel', 'hello');
greet('jack');
print 10 * '*', '返回值', 10 * '*';
def returnNone():
pass;
print returnNone(); # None
def returnNone2():
1 + 3;
print returnNone2(); # None
def returnNone3():
return None;
print returnNone3(); # None
def add(a, b):
return a + b;
print add(3,5); # 8
print 10 * '*', '变量的作用域', 10 * '*';
x = 3;
def func():
x = 5;
func(); # not change global x
print 'x is still', x; #3
def func2():
global x;# tell it's the global x
x = 10;
func2(); # change global x
print 'x change to', x; #10
print 20 * '*';
x = 0;
def func3():
x = 1;
y = 'y~~~';
def func4():
print x; # 0, global is put before this line
global x; # always the outest.
x = 2;
print y;# can read from outerside
print x; #1
func4();
print x; #1
func3();
print 'x change to', x; # 2
# 如果你的某个函数有许多参数，
# 而你只想指定其中的一部分，
# 那么你可以通过命名来为这些参数赋值——这被称作 关键参数
# ——我们使用名字（关键字）而不是位置（我们前面所一直使用的方法）来给函数指定实参。
print 10 * '*', '关键参数', 10 * '*';
def keyParamFunc(a, b=5, c=10):
print 'a is', a, 'and b is', b, 'and c is', c
keyParamFunc(3, 7)
keyParamFunc(25, c=24)
keyParamFunc(c=50, a=100)
print 10 * '*', '函数文档', 10 * '*';
def printMax(x, y):
'''函数描述： Prints the maximum of two numbers.
The two values must be integers.'''
x = int(x) # convert to integers, if possible
y = int(y)
if x > y:
print x, 'is maximum'
else:
print y, 'is maximum'
printMax(3, 5)
print printMax.__doc__
# lamda 匿名函数,有点类似闭包
print 10 * '*', 'lambda', 10 * '*';
print (lambda a,b: a+b)(1,3); #4
print map(lambda x: x * x, [1,2,3]); # [1, 4, 9]
a,b,c = (lambda: (1,3,5))();
print a,b,c;