Python核心编程v2.0 第9章习题答案（下）

12.
a)过程中还是沿用的db进行处理，开始和结束用文件生成及读取db

# -*- coding: utf-8 -*-#coding = utf-8import timedb = {}#从文件中读取用户信息def readfile():    name = raw_input('filename:')    f = open(name,'r')    for eachline in f:        #去掉最后的换行，否则会多出一个为空的用户        eachline = eachline.rstrip()        li = eachline.split(':')        infor = []        infor.append(li[1])        infor.append(li[2])        db[li[0]]=infor#将db写入文件def writefile():    name = raw_input('filename for write:')    f = open(name,'w')    for keys in db:        f.write(keys+':')        f.write(str(db[keys][0])+':')        f.write(str(db[keys][1])+'\n')    f.close()def newuser():    prompt = 'login desired:'    while True:        name = raw_input(prompt)        if db.has_key(name):            prompt = 'name taken,try another'            continue        else:            break    pwd = raw_input('passwd:')    #存下新用户第一次登录时间    db[name] = [pwd,time.strftime("%Y %m %d %H %M", time.localtime())]def olduser():    name = raw_input('login:')    pwd = raw_input('passwd:')    passwd = db[name][0]    if passwd == pwd:        print 'welcome back',name        #记录登录时间        ti = time.strftime("%Y %m %d %H %M", time.localtime())        lis1 = ti.split(' ')        lis2 = db[name][1].split(' ')        # print lis1        # print lis2        #打印上次登录时间        print 'you alraedy logged in at %s' %db[name][1]        #更新登录时间        db[name][1] = ti    else:        print 'login incorrect'def delete():    name = raw_input('you want to delete')    del db[name]    print '%s has been delet'% namedef showuser():    for key in db:        print key,        print db[key][0],        print db[key][1]def showmenu():    readfile()    prompt = '''    N    E    Q    D    S    enter choice:    '''    done = False    while not done:        chosen = False        while not chosen:            try :                choice = raw_input(prompt).strip()[0]            except(EOFError,KeyboardInterrupt):                choice = 'Q'            print 'you picked :[%s]' % choice            if choice not in 'NEQDS':                print 'invaild option'            else:                chosen = True        if choice == 'Q':done = True        if choice == 'N':newuser()        if choice == 'E':olduser()        if choice == 'D':delete()        if choice == 'S':showuser()    writefile()if __name__ == '__main__':    showmenu()

b)
只贴了有改动部分。

...import pickle#从文件中读取用户信息def readfile():    name = raw_input('filename:')    f = open(name,'r')    global db    db = pickle.load(f)    f.close()#将db写入文件def writefile():    name = raw_input('filename for write:')    f = open(name,'w')    pickle.dump(db,f)    f.close()

c)
在设置了writeback为True的情况下，当db更改后，会自动的写入缓存，关闭后写入文件中，可以去掉writefile函数

#从文件中读取用户信息def readfile():    name = raw_input('filename:')    global db    db = shelve.open(name,writeback=True)

13.
命令行参数是调用某个程序时除程序名以外的其他参数。pycharm下在terminal窗口调用python filename name1 name2 name3可以使用

    print 'you entered',len(sys.argv),'arguments'    print 'they are',str(sys.argv)

结果

D:\pycharm\LanguageStudy>python langstudy.py name1 name2 name3you entered 4 argumentsthey are ['langstudy.py', 'name1', 'name2', 'name3']

14.

# -*- coding: utf-8 -*-#coding = utf-8from __future__ import divisionimport sysrecord = ''def count(list) :    list[0] = int(list[0])    list[2] = int(list[2])    if list[1] == '+' :        r = list[0]+list[2]    elif list[1] == '-' :        r = list[0]-list[2]    else:        print "wrong operator"    return rdef writefile():    f = open('ar.txt','w')    f.write(record)    f.close()def showinscreen():    f = open('ar.txt','r')    for eachline in f:        print eachline.rstrip()    f.close()    f = open('ar.txt','w')    f.close()if __name__ == '__main__':    if len(sys.argv ) == 4:        list = []        list.append(sys.argv[1])        list.append(sys.argv[2])        list.append(sys.argv[3])        record = record+sys.argv[1]+sys.argv[2]+sys.argv[3]+'\n'        result = count(list)        record = record + str(result)+'\n'        print result        writefile()    elif sys.argv[1] == 'print':        showinscreen()

15.

def copy(name1,name2):    fin = open(name1,'r')    content = fin.readlines()    fin.close()    fout = open(name2,'a')    #追加模式打开后，指针还是在文件开头位置，需要位移到文件末尾进行添加    fout.seek(0,2)    for i in content:        fout.write(i)    fout.close()if __name__ == '__main__':    name1 = raw_input('name1:')    name2 = raw_input('name2:')    copy(name1,name2)

16.
读文件时候的指针有点不好控制，写了一个复杂度高一些的实现方法，先读出来处理后再写入

# -*- coding: utf-8 -*-#coding = utf-8def nomorethan10(name1):    f = open(name1,'r')    linelist = []    for eachline in f:        if len(eachline)>10:            index1 = eachline.rfind(' ',0,10)            index2 = eachline.find(' ',10,len(eachline)-1)            if 10 - index1> index2-10:                line = eachline[0:index2]+'\n'+eachline[index2:]            else:                line = eachline[0:index1]+'\n'+eachline[index1:]            linelist.append(line.rstrip('\n'))        else:            line = eachline            linelist.append(line)    f.close()    f = open(name1,'w')    for i in linelist:        f.write(i+'\n')    f.close()if __name__ == '__main__':    name1 = raw_input('name:')    nomorethan10(name1)

17.
没写GUI，大概写了写逻辑

# -*- coding: utf-8 -*-#coding = utf-8import sysdef creatfile(name,contlis):    f = open(name,'w')    for i in contlis:        f.write(i)        f.write('\n')    f.close()def showfile():    for i in lines:        print i.rstrip()def editfile(number):    f = open(name,'r')    lines = f.readlines()    f.close()    line = lines[number-1]    print line    line = raw_input('input your new line')    lines[number-1] = line.rstrip()    return linesdef savefile():    f = open(name,'w')    for i in lines:        f.write(i)    f.close()if __name__ == '__main__':    while True:        print 'crear file:c'        print 'show file:s'        print 'edit file:e'        print 'save file:a'        print 'quit:q'        order = raw_input('order:')        if order == 'c':            name = raw_input('name:')            content = raw_input('content:')            contlis = content.split('.')            lines = contlis            creatfile(name,contlis)        elif order == 's':            showfile()        elif order == 'e':            number = int(raw_input('line number:'))            lines = editfile(number)        elif order == 'a':            savefile()        elif order == 'q':            break

18.

# -*- coding: utf-8 -*-def checkchar(char,name):    f = open(name,'r')    index = 0    for eachline in f:        count = eachline.count(char)        index = index+count    f.close()    return indexif __name__ == '__main__':    num = int(raw_input('input a number'))    char = chr(num)    name = raw_input('name')    print checkchar(char,name)

19.
f.write函数写入后会覆盖后一个字节，所以先用list存了一下生成的数据在写入

# -*- coding: utf-8 -*-import  randomdef creatfile(char,number,lenth):    ls = []    i = 0    while i< lenth - number:        ran = random.randint(0,255)        if chr(ran) == char:            ran = ran+1        ls.append(chr(ran))        i = i+1    for j in range(number):        ranlen = random.randint(0,lenth)        ls.insert(ranlen,char)    f = open(name,'wb')    for i in ls:        f.write(i)    f.close()if __name__ == '__main__':    num = int(raw_input('input a number'))    char = chr(num)    name = raw_input('name')    creatfile(char,2,5)

20.

# -*- coding: utf-8 -*-import  gzipdef makezip(name,zipname):    f_in = open(name, 'rb')    f_out = gzip.open(zipname, 'wb')    f_out.writelines(f_in)    f_out.close()    f_in.close()def readzip(zipname):    f_in = gzip.open(zipname, 'rb')    file_content = f_in.read()    f_out = open('tr.txt','wb')    f_out.write(file_content)    f_in.close()    f_out.close()if __name__ == '__main__':    name = 'ar.txt'    zipname = 'ar.gz'    makezip(name,zipname)    readzip(zipname)

21.
创建和添加是一样，只是mode一个为’w’一个为’a’和普通文件相同。sys.path[0]为调用该py程序的目录。

# -*- coding: utf-8 -*-import zipfileimport sysdef addzip(file2):    f = zipfile.ZipFile(name, 'a', zipfile.ZIP_DEFLATED)    f.write(file2)    f.close()def readzip(file2):    f = zipfile.ZipFile(name, 'r')    f.extract(file2,sys.path[0])    f.close()if __name__ == '__main__':    name = 'ar.zip'    file = 'ar.txt'    file2 = 'tr.txt'    addzip(file2)    readzip(file2)

22.
zipfile返回的date_time属性为6元元组，time.mktime接收9元，补充了3个0

# -*- coding: utf-8 -*-import zipfileimport timeadd = [0,0,0]def readzip(file):    zp = zipfile.ZipFile(file,'r')    for file in zp.namelist():        info = zp.getinfo(file)        print file        print info.compress_size,        print info.file_size        print info.file_size/info.compress_size        print info.date_time        ti  = list(info.date_time)        ti.extend(add)        secs = time.mktime(ti)        time_a = time.ctime(secs)        print time_aif __name__ == '__main__':    readzip('tr.zip')

23.
tarfile的open函数可以选择不同模式，在模式中已经实现了对gzip和bzip2的支持。’w’模式再次打开后写入会覆盖，’a’模式不可以加压缩参数，如果需要添加，比较麻烦的思路是解压，再全部写进去一次。’a’模式对gzip好后的文件也做不进去添加。
在这里贴一下模式列表：

'r' or 'r:*'   Open for reading with transparent compression (recommended).'r:'   Open for reading exclusively without compression.'r:gz'   Open for reading with gzip compression.'r:bz2'   Open for reading with bzip2 compression.'a' or 'a:'   Open for appending with no compression. The file is created if it does not exist.'w' or 'w:'   Open for uncompressed writing.'w:gz'   Open for gzip compressed writing.'w:bz2'   Open for bzip2 compressed writing.

# -*- coding: utf-8 -*-import tarfileimport sysdef addzip(file2):    f = tarfile.open(name,'w:gz')    f.add(file2)    f.close()def readzip(file2):    f = tarfile.open(name,'r:gz')    f.extract(file2,sys.path[0])    f.close()if __name__ == '__main__':    name = 'ar.tar'    file = 'ar.txt'    addzip(file)    readzip(file)

24.
实现了tar转移到zip，反过来思路类似。生成了中间文件。

# -*- coding: utf-8 -*-import tarfileimport zipfileimport sysdef readtar(file2):    f = tarfile.open('ar.tar','r:gz')    if file2 in f.getnames():        f.extract(file2,sys.path[0])    else:        fc = open(file2,'w')        fc.close()    f.close()def addzip(file2):    f = zipfile.ZipFile('br.zip', 'a', zipfile.ZIP_DEFLATED)    f.write(file2)    print f.namelist()    f.close()def move(name):    readtar(name)    addzip(name)if __name__ == '__main__':    move('haha.txt')

25.
题目的意思就是第一个输入的压缩文件直接解压到提供的目录，然后后面的压缩文件在该目录下创建同名文件夹，再解压到同名文件夹里面

# -*- coding: utf-8 -*-import tarfileimport sysimport osimport zipfiledef readzip(name,di):    f = zipfile.ZipFile(name, 'r')    for i in f.namelist():        f.extract(i,di)    f.close()def readtar(name,di):    f = tarfile.open(name,'r:gz')    for i in f.getnames():        f.extract(i,di)    f.close()def makefile(lis,di):    if lis[0].endswith('.zip'):        readzip(lis[0],di)    elif  lis[0].endswith('.tar'):        readtar(lis[0],di)    i = 1    while i <len(lis):        index = lis[i].index('.')        name = lis[i][0:index]        di_n = di+'\\'+name        os.mkdir(di_n)        if lis[i].endswith('.zip'):            readzip(lis[i],di_n)        elif lis[i].endswith('.tar'):            readtar(lis[i],di_n)        i = i+1if __name__ == '__main__':    lis = ['ar.zip','sr.zip','dr.tar']    di = sys.path[0]    makefile(lis,di)