元组和列表十分类似，只不过元组和字符串一样是 不可变的 即你不能修改元组。元组通过圆
括号中用逗号分割的项目定义。元组通常用在使语句或用户定义的函数能够安全地采用一组值
的时候，即被使用的元组的值不会改变。
#!/usr/bin/python
# Filename: using_tuple.py
zoo = ('wolf', 'elephant', 'penguin')
print 'Number of animals in the zoo is', len(zoo)
new_zoo = ('monkey', 'dolphin', zoo)
print 'Number of animals in the new zoo is', len(new_zoo)
print 'All animals in new zoo are', new_zoo
print 'Animals brought from old zoo are', new_zoo[2]
print 'Last animal brought from old zoo is', new_zoo[2][2]
$ python using_tuple.py
Number of animals in the zoo is 3
Number of animals in the new zoo is 3
All animals in new zoo are ('monkey', 'dolphin', ('wolf', 'elephant', 'penguin'))
Animals brought from old zoo are ('wolf', 'elephant', 'penguin')
Last animal brought from old zoo is penguin
含有0个或1个项目的元组。一个空的元组由一对空的圆括号组成，如myempty = ()。然而，含
有单个元素的元组就不那么简单了。你必须在第一个（唯一一个）项目后跟一个逗号，这样
Python才能区分元组和表达式中一个带圆括号的对象。即如果你想要的是一个包含项目2的元
组的时候，你应该指明singleton = (2 , )。
元组与打印语句
#!/usr/bin/python
# Filename: print_tuple.py
age = 22
name = 'Swaroop'
print '%s is %d years old' % (name, age)
print 'Why is %s playing with that python?' % name
输出
$ python print_tuple.py
Swaroop is 22 years old
Why is Swaroop playing with that python?