第7章 函数

longingo

例7.1 定义函数
#!/usr/bin/python
# Filename: function1.py
def sayHello():
    print 'Hello World!' # block belonging to the function
sayHello() # call the function
例7.2 使用函数形参
#!/usr/bin/python
# Filename: func_param.py
def printMax(a, b):
    if a > b:
        print a, 'is maximum'
    else:
        print b, 'is maximum'
printMax(3, 4) # directly give literal values
x = 5
y = 7
printMax(x, y) # give variables as arguments
例7.3 使用局部变量
#!/usr/bin/python
# Filename: func_local.py
def func(x):
    print 'x is', x
    x = 2
    print 'Changed local x to', x
x = 50
func(x)
print 'x is still', x
例7.4 使用global语句
#!/usr/bin/python
# Filename: func_global.py
def func():
    global x
    print 'x is', x
    x = 2
    print 'Changed local x to', x
x = 50
func()
print 'Value of x is', x
例7.5 使用默认参数值
#!/usr/bin/python
# Filename: func_default.py
def say(message, times = 1):
    print message * times
say('Hello')
say('World', 5)
例7.6 使用关键参数
#!/usr/bin/python
# Filename: func_key.py
def func(a, b=5, c=10):
    print 'a is', a, 'and b is', b, 'and c is', c
func(3, 7)
func(25, c=24)
func(c=50, a=100)
例7.7 使用字面意义上的语句
#!/usr/bin/python
# Filename: func_return.py
def maximum(x, y):
    if x > y:
        return x
    else:
        return y
print maximum(2, 3)
例7.8 使用DocStrings
#!/usr/bin/python
# Filename: func_doc.py
def printMax(x, y):
    '''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__





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