python例子

例一：for循环

for i in range(1,100):

        if i==23:

            print "great,%s you got your lucky number:" %(i)

            break

        else:

            print 'the number is :',i

运行：windows下 切换到目录下 Python xunhuan.py

linux 下      cd到目录下  Python xunhuan.py

例二：阶乘的例子

n=int(input('Enter an integer >=0:'))

fact=

for i in range(,n+):

    fact=fact*i;

print(str(n)+'factorial is'+str(fact))

例三：while循环

total=

s=raw_input('Enter a number(or done):')

while s !='done':

    num=int(s)

    total=total+num

    s=raw_input('Enter a number(or done):')

print('The sum is '+str(total))

例四：九九乘法表

for i in range(,):

    for j in range(,i+):

        print j, 'x', i, '=', j*i, '\t',

    print '\n'

print 'done'
        

例五、函数定义

import math

def move(x,y,step,angle=):

    nx=x+step*math.cos(angle)

    ny=y+step*math.sin(angle)

    return nx,ny

x, y = move(, , , math.pi / )

print x,y

例六、可变参数函数

import math

def calc(*numbers):

    sum =

    for n in numbers:

        sum = sum + n * n

    return sum

y=calc(, ,,)

print y

例七：递归函数

def fact(n):

    if n==:

        return

    return n*fact(n-)

y=fact()

print y

例八：尾递归的递归函数

只返回函数本身

def fact(n):

    return fact_iter(, , n)

def fact_iter(product, count, max):

    if count > max:

        return product

    return fact_iter(product * count, count + , max)

y=fact()

print y

例九：高阶函数

def add(x, y, f):

    return f(x) + f(y)

print add(-, , abs)

把函数作为参数传入，这样的函数称为高阶函数，函数式编程就是指这种高度抽象的编程范式。

例十：字典

color={'red':,'blue':,'gree':}

print color['gree']

color['gree']=

print color

例十一：一个ping程序

import subprocess

cmd="cmd.exe"

begin=

end=

while begin<end:

    p=subprocess.Popen(cmd,shell=True,stdout=subprocess.PIPE,

                   stdin=subprocess.PIPE,

                   stderr=subprocess.PIPE)

    p.stdin.write("ping 10.10.0."+str(begin)+"\n")

    p.stdin.close()

    p.wait()

    begin=begin+

    print "execution result: %s"%p.stdout.read()

例十二：os模块

#!/usr/bin/env python

# -*- coding:gbk -*-

import os

for fileName in os.listdir ( 'd:\\' ):

    print fileName

例十三：创建目录

#!/usr/bin/env python

# -*- coding:gbk -*-

#Python对文件系统的操作是通过os模块实现

import os

for fileName in os.listdir ( 'd:\\' ):

    print fileName

print "**************"

os.mkdir("d:\\dgx")

for fileName in os.listdir ( 'd:\\' ):

    print fileName

例十四：写入读取的内容到文件

#!/usr/bin/env python

import os

ls=os.linesep

while True:

    fname = raw_input('Enter file name: ')

    if os.path.exists(fname):

        print "Error:%s already exists "

    else:

        break

all = []

print "\nEnter lines('.'by itself to quit)"

while True:

    entry=raw_input('>')

    if entry =='.':

        break

    else:

        all.append(entry)

fobj=open(fname,'w')

fobj.write('\n'.join(all))

fobj.close()

print 'Done'
        

例十五：读取文件内容

#!/usr/bin/env python

fname=raw_input('Enter filename:')

try:

    fobj=open(fname,'r')

except IOError,e:

    print "*******file open error:",e

else:

    for eachLine in fobj:

        print eachLine,

    fobj.close()

例十六：第一个main

#-*-coding:utf--*-

import sys

def Main():

    sys.stdout.write("开始程序\n")

    str1='i am "python"\n'

    str2="i am 'python'\r"

    str3="""

            i'm "python",

            <a href="http://www.sina.com.cn"></a>

            """

    print str1,str2,str3

if  __name__ == '__main__':

    Main()

例十七：函数的默认参数与返回值

#-*-coding:utf--*-

import sys

def arithmetic(x=,y=,operator="+"):

    result={

        "+":x+y,

        "-":x-y,

        "*":x*y,

        "/":x/y

    }

    return result.get(operator)

if __name__=="__main__":

    print arithmetic(, )

    print arithmetic(, , "/")