@author : istory85

第九章 数据结构

1.字符串的方法

name = 'Swaroop'
if name.startswith('Swa'):
    print 'Yes, the string starts with "Swa"'
if 'a' in name:
    print 'Yes, it contains the string "a"'
if name.find('war') != -1:
    print 'Yes, it contains war'
delimiter = '_*_'
mylist = ['Brazil', 'Russia', 'Japan', 'China']
print delimiter.join(mylist)

第十章 编写一个python脚本

1. 备份脚本 版本4.0

import os
import time
source = ['/root/a.txt', '/root/b.txt']
target_dir = '/root/backup/'
today = target_dir + time.strftime('%Y%m%d')
now = time.strftime('%H%M%S')
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)
    print 'Successfully created directory', 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'

第十一章 面向对象的编程

1.定义一个简单的人 类

class Person:
    def __init__(self, name):
        self.name = name
    def sayHi(self):
        print 'Hello, my name is', self.name
p = Person('Swaroop')
p.sayHi()

2.测试一个类

class Person:
    population = 0
    def __init__(self, name):
        self.name = name
        print '(Initializing %s)' % self.name
        Person.population += 1
    def __del__(self):
        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()
kalam = Person('Abdul Kalam')
kalam.sayHi()
kalam.howMany()
swaroop.sayHi()
swaroop.howMany()
kalam.__del__()
kalam.howMany()
swaroop.__del__()
swaroop.howMany()

3.继承 ,由学校成员类继承出老师类和学生类

class SchoolMember:
    def __init__(self, name, age):
        self.name = name
        self.age = age
        print '(Initialized SchoolMemeber: %s)' % self.name
    def tell(self):
        print 'Name:"%s" Age:"%s"' % (self.name, self.age)
class Teacher(SchoolMember):
    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):
    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, 3000)
s = Student('Swaroop', 22, 75)
print   #prints a blank line
members = [t, s]
for member in members:
    member.tell()

第十二章 文件的输入，输出

1.一首简单小诗歌的打印

poem = '''\
Programing is fun
when the work is done
if you wanna makeyour work also fun:
        use Python!
'''
f = file('poem.txt', 'w')
f.write(poem)
f.close()
f = file('poem.txt')
while True:
    line = f.readline()
    if len(line) == 0:
        break
    print line,
f.close()

2.储存器

import cPickle as p
shoplistfile = 'shoplist.data' #name
shoplist = ['apple', 'mango', 'carrot'] #thing
f = file(shoplistfile, 'w') #read
p.dump(shoplist, f) #store
f.close() #close
del shoplist  #del thin
f = file(shoplistfile) #read
storedlist = p.load(f) #load and read
print storedlist #show

第十三章 异常

1.处理异常

import sys
try:
    s = raw_input('Enter something --> ')
except EOFError:
    print '\nWhy did you do an EOF on me?'
    sys.exit()
except:
    print '\nSome error/exception occurred.'
print 'Done'

2.如何引发异常

class ShortInputException(Exception):
    '''A user-defined exception class.'''
    def __init__(self, length, atleast):
        Exception.__init__(self)
        self.length = length
        self.atleast = atleast
try:
    s = raw_input('Enter something --> ')
    if len(s) < 3:
        raise ShortInputException(len(s), 3)
except EOFError:
    print '\nWhy did you do an EOF on me？'
except ShortInputException, x:
    print 'ShortInputException: The input was of length %d, \
was expecting at least %d' % (x.length, x.atleast)
else:
    print 'No exception was raised'

3.运行过程中手动中止，ctr-c，会发生键盘中断异常

import time
try:
    f = file('poem.txt')
    while True:
        line = f.readline()
        if len(line) == 0:
            break
        time.sleep(2)
        print line,
finally:
    f.close()
    print 'Cleaning up...closed the file'

第十四章 python标准库

1.sys模块 — 命令行参数

import sys
def readfile(filename):
    '''Print a file to the standard output.'''
    f = file(filename)
    while True:
        line = f.readline()
        if len(line) == 0:
            break
        print line,
    f.close()
if len(sys.argv) < 2:
    print 'No action specified.'
    sys.exit()
if sys.argv[1].startswith('--'):
    option = sys.argv[1][2:]
    if option == 'version':
        print 'Version 1.2'
    elif option == 'help':
        print '''\
This program prints files to the standard output.
Any number of files can be specified.
Options include:
  --version  :  Prints the version number
  --help     :  Display this help'''
    else:
        print 'Unkown option.'
    sys.exit()
else:
    for filename in sys.argv[1:]:
        readfile(filename)

2.os 模块

os.name --指示当前使用平台  对windows, 返回'nt'，对于linux等，返回'posix'.
os.getcwd()得到当前工作目录 os.getenv()/putenv()  读取和设置环境变量
os.listdir()返回指定目录下的所有文件和目录名    os.remove()
os.system()运行shell脚本    os.sep取代了当前系统的路径分隔符
os.linesep给出当前平台的行终止符   os.path.split()返回一个路径的目录名和文件名
os.path.isfile()/isdir()判断给出的路径是一个文件还是一个目录
os.path.existe()检验给出的路径是否真实的存在

第十五章 更多python的内容

1.特殊的方法

__init__    __del__     __str__     __lt__
__getitem__ __len__

2.单语句块 / 列表综合

listone = [2, 3, 4,100]
listtwo = [2*i for i in listone if i > 2]
print listtwo

3.在函数中接受元组和列表，*前缀存储为一个元组，**前缀则存储为一个字典的键值对

def powersum(power, *args):
    '''Return the sum of each argument raised to
specified power.'''
    total = 0
    for i in args:
        total += pow(i, power)
    return total
print powersum(2, 3, 4)
print powersum(2, 10)

4.lambda 形式 lambda参数:表达式

def make_repeater(n):
    return lambda s: s*n
twice = make_repeater(2)
print twice('word')
print twice(5)

5.exec和eval语句 exec来执行储存在字符串和文件中的python语句。 eval来计算存储在字符串中的有效python表达式

exec 'print "Hello World"'
print eval ('2*3')

6.assert语句 用来声明某个条件是真的

mylist = ['item']
assert len(mylist) >= 1
mylist.pop()
assert len(mylist) >= 1

7.repr函数，用来取得对象的规范字符串表示

i = []
i.append('item')
print `i`
print repr(i)