python简要

python用冒号代替{}开启语句块

1. /usr/bin/python 加在脚本的头部， ./脚本

2. help("str") : 查看命令帮助

3. '''三引号可以打印换行字符串
   
   print('\n') 可以打印换行

4. 表达式打印
   
   s = 10
   
   print 'asdasd',s

5. if循环，python没有switch，取而代之的是字典

#!/usr/bin/python
guess = int(raw_input('Enter number ...'))
if guess==1:
    print '1'
elif guess ==2:
    print '2'
else:
    print '3'

1. while循环，有可选的else从句

#!/usr/bin/python
flag = True
num=23
while flag:
    guess = int(raw_input('enter number'))
    if guess == num:
        print 'yes'
        flag = False
    elif guess>num:
        print 'big'
    else:
        print 'small'
else:
    print 'loop end'

1. for

for i in range(1,5):
    print i

函数 ：

#!/usr/bin/python
def getMax(a,b):
    if a>b:
        print a,'is max'
    else:
        print b,'is max'

getMax(1,'as')

67

函数内部声明global变量，让该变量从上下文钟获取变量值

函数的返回值需要return声明，如果不声明，默认在在结尾return None

模块

1. sys模块带有环境相关的参数

import sys
print 'console arg:'
for i in sys.argv:
    print i

print 'python path is',sys.path

列出模块的属性方法 ： dir

删除模块的属性方法 ： del

列表 ： [elem1,elem2]

del list[index]：删除列表的元素

len(listname)：list长度

applist = ['apple','orange','carrot']
print applist

for i in applist:
    print i

del applist[0]         #['orange', 'carrot']
applist.append('wo')   #['orange', 'carrot', 'wo']
print applist
applist.sort()         #['carrot', 'orange']
print applist

元祖：不可变的列表

zoo = ['wolf',1]

print zoo
print len(zoo)

newzoo = [2,3,zoo]  #2
print newzoo[2][1]  #1

占位打印

age = 22
name = 'zhangsan'

print '%s is %d' % (name,age)

字典：map

{k:v,k2:v2}

map1 = {"zs":24,"lisi":25}
print map1["zs"]   #24
del map1["zs"]
print map1         #{'lisi': 25}

for name,age in map1.items():
    print '%s is %d' % (name,age)      #lisi is 25

if map1.has_key('lisi'):
    print 'lisi is %d' % map1['lisi']  #lisi is 25

序列：元组和列表都是序列

序列2中操作：

（1）索引操作：用脚标获取元素

（2）切片操作：2个角标确定切片，a:b,表示从a开始，到b结束，不包含b角标的子序列

python备份文件

import time
import os

source = ['/home/swaroop/byte','/home/swaroop/bin']
target_dir = '/mnt/e/backup/'
today = target_dir + time.strftime('%Y%m%d')
now = time.strftime('%H%M%S')   #文件明中加上注释
comment = raw_input('Enter a comment --> ')

if len(comment)==0:
    target = today + os.sep + now + '.zip'
else:
    target = today + os.sep + now + '_' + comment.replace('','_') + 'zip'

if not os.path.exists(today):
    os.mkdir(today)

zip_command = "zip -qr '%s' %s" % (target, ' '.join(source))

if os.system(zip_command)==0:
    print 'Successful backup to', target
else:
    print 'Backup FAILED'

类

假设一个类MyClass，他的对象MyObject

类中的方法的第一个参数必须是self对象，即使是空参函数，也要有self

当对象调用MyObject.method(arg1, arg2)时，python会自动转换为MyClass.method(MyObject, arg1,arg2)

构造方法：

init(self,param):self.param = param

消亡方法

del

# -*- coding: utf-8 -*
class Person:
    # 类变量
    population = 0
    # 对象变量
    def __init__(self, name):   #对象初始化时调用
        self.name = name
        print '(Initializing %s)' % self.name
        Person.population += 1

    def __del__(self):          # 对象消亡，清空内存时使用
        print '%s says bye.' % self.name
        Person.population -= 1
        if Person.population == 0:
            print 'I am the last one.'
        else:
            print 'There are still %d people left.' % Person.population

    def sayHi(self):
        print 'Hi, my name is %s.' % self.name

    def howMany(self):
        if Person.population == 1:
            print 'I am the only person here.'
        else:
            print 'We have %d persons here.' % Person.population

swaroop = Person('Swaroop')
swaroop.sayHi()
swaroop.howMany()

继承

把父类的类名作为一个元组放在声明子类的后面

class SchoolMember:
    '''Represents any school member.'''
    def __init__(self, name, age):
        self.name = name
        self.age = age
        print '(Initialized SchoolMember: %s)' % self.name

    def tell(self):
        '''Tell my details.'''
        print 'Name:"%s" Age:"%s"' % (self.name, self.age)

class Teacher(SchoolMember):
    '''Represents a teacher.'''
    def __init__(self, name, age, salary):
        SchoolMember.__init__(self, name, age)
        self.salary = salary
        print '(Initialized Teacher: %s)' % self.name

    def tell(self):
        SchoolMember.tell(self)
        print 'Salary: "%d"' % self.salary

class Student(SchoolMember):
    '''Represents a student.'''
    def __init__(self, name, age, marks):
        SchoolMember.__init__(self, name, age)
        self.marks = marks
        print '(Initialized Student: %s)' % self.name

    def tell(self):
        SchoolMember.tell(self)
        print 'Marks: "%d"' % self.marks

t = Teacher('Mrs. Shrividya', 40, 30000)
s = Student('Swaroop', 22, 75)
print # prints a blank line
members = [t, s]
for member in members:
    member.tell() # works for both Teachers and Students

异常

try：

except EOFError:

except:

相当于： try .. catch .. catch ..

try:

finally:

eval("2+3")

5

exec 'print "hello world"'

hello world