>>> while True:
...     try:
...         x = int(raw_input("Please enter a number: "))
...         break
...     except ValueError:
...         print "Oops!  That was no valid number.  Try again..."
...

... except (RuntimeError, TypeError, NameError):
...     pass

while True:try:x=input('please enter the first number:')y=input('please enter the second number:')print 1.*x/yexcept:print 'something wrong happened! enter again!'else:break

for arg in sys.argv[1:]:try:f = open(arg, 'r')except IOError:print 'cannot open', argelse:print arg, 'has', len(f.readlines()), 'lines'f.close()

>>> raise NameError('HiThere')
Traceback (most recent call last):File "<stdin>", line 1, in ?
NameError: HiThere

>>> class MyError(Exception):
...     def __init__(self, value):
...         self.value = value
...     def __str__(self):
...         return repr(self.value)
...
>>> try:
...     raise MyError(2*2)
... except MyError as e:
...     print 'My exception occurred, value:', e.value
...
My exception occurred, value: 4
>>> raise MyError('oops!')
Traceback (most recent call last):File "<stdin>", line 1, in ?
__main__.MyError: 'oops!'

>>> def divide(x, y):
...     try:
...         result = x / y
...     except ZeroDivisionError:
...         print "division by zero!"
...     else:
...         print "result is", result
...     finally:
...         print "executing finally clause"
...
>>> divide(2, 1)
result is 2
executing finally clause
>>> divide(2, 0)
division by zero!
executing finally clause
>>> divide("2", "1")
executing finally clause
Traceback (most recent call last):File "<stdin>", line 1, in ?File "<stdin>", line 3, in divide
TypeError: unsupported operand type(s) for /: 'str' and 'str'

class ClassName:'类的帮助信息'   #类文档字符串class_suite  #类体

class Student(object):def __init__(self, name, score):self.name = nameself.score = scoredef print_score(self):print '%s: %s' % (self.name, self.score)

#!/usr/bin/python
# -*- coding: UTF-8 -*-class Employee:'所有员工的基类'empCount = 0def __init__(self, name, salary):self.name = nameself.salary = salaryEmployee.empCount += 1def displayCount(self):print "Total Employee %d" % Employee.empCountdef displayEmployee(self):print "Name : ", self.name,  ", Salary: ", self.salaryprint "Employee.__doc__:", Employee.__doc__
print "Employee.__name__:", Employee.__name__
print "Employee.__module__:", Employee.__module__
print "Employee.__bases__:", Employee.__bases__
print "Employee.__dict__:", Employee.__dict__

#!/usr/bin/python
# -*- coding: UTF-8 -*-class Parent:        # 定义父类parentAttr = 100def __init__(self):print "调用父类构造函数"def parentMethod(self):print '调用父类方法'def setAttr(self, attr):Parent.parentAttr = attrdef getAttr(self):print "父类属性 :", Parent.parentAttrclass Child(Parent): # 定义子类def __init__(self):print "调用子类构造方法"def childMethod(self):print '调用子类方法 child method'c = Child()          # 实例化子类
c.childMethod()      # 调用子类的方法
c.parentMethod()     # 调用父类方法
c.setAttr(200)       # 再次调用父类的方法
c.getAttr()          # 再次调用父类的方法

#!/usr/bin/python
# -*- coding: UTF-8 -*-class Parent:        # 定义父类def myMethod(self):print '调用父类方法'class Child(Parent): # 定义子类def myMethod(self):print '调用子类方法'c = Child()          # 子类实例