python核心編程第二版第9章習題答案

1、91. 文件過濾. 顯示一個文件的所有行, 忽略以井號( # )開頭的行. 這個字符被用做Python , Perl, Tcl, 等大多腳本文件的注釋符號.附加題: 處理不是第一個字符開頭的注釋.答案：f = open('test1.txt','r')for eachline in f:if eachline0 = '#':continueelif '#' in eachline:loc = eachline.find('#')print eachline:locelse:print eachline,92. 文件

2、訪問. 提示輸入數(shù)字 N 和文件 F, 然后顯示文件 F 的前 N 行.答案：N = int(raw_input('Enter a number: ')f = raw_input('Enter filename :')f1 = open(f,'r')allline = f1.readlines()f1.close()for i in range(N):print alllinei,93. 文件信息. 提示輸入一個文件名, 然后顯示這個文本文件的總行數(shù).答案：f = raw_input('Enter filename :')f1 =

3、 open(f,'r')sum = 0for i in f1:sum += 1print sumf = raw_input('Enter filename :')f1 = open(f,'r')sum = 0for i in f1:sum += 1print sum方法二:f = raw_input('Enter filename :')f1 = open(f,'r')allline = f1.readlines()f1.close()print len(allline)94. 文件訪問. 寫一個逐頁顯示文本文件的

4、程序. 提示輸入一個文件名, 每次顯示文本文件的 25 行, 暫停并向用戶提示"按任意鍵繼續(xù).", 按鍵后繼續(xù)執(zhí)行.答案：f = raw_input('Enter filename :')f1 = open(f,'r')allline = f1.readlines()f1.close()sum = 0for i in allline:print i,sum += 1if sum = 25:a = raw_input("press any key to continue:")sum = 0方法二import os F=raw

5、_input('pls input a file name:') n=0 f=open(F,'r') for i in f: print i, n+=1 if n=25: n=0 os.system('pause') f.close() 9-5 考試成績，改進你的考試成績問題（練習5-3和6-4），要求能從多個文件中讀入考試成績。文件的數(shù)據(jù)格式由你自己決定。答案：f = open('test1.txt','r')scores = for i in f:if 0 <= int(i.strip()<= 10

6、0:scores.append(int(i.strip()else:print 'score wrong ,please again'if int(i.strip() < 60:print 'score is E',ielif int(i.strip() < 70:print 'score is D',ielif int(i.strip() < 80:print 'score is C',ielif int(i.strip() < 90:print 'score is B',ielse:pr

7、int 'score is A',if.close()print 'average score is %.2f' % (sum(scores)/len(scores)96. 文件比較. 寫一個比較兩個文本文件的程序. 如果不同, 給出第一個不同處的行號和列號.答案：f1 = raw_input('Enter a filename: ')f2 = raw_input('Enter a filename: ')F1 = open(f1,'r')F2 = open(f2,'r')F1allline = F

8、1.readlines()F2allline = F2.readlines()F1.close()F2.close()len1 = len(F1allline)len2 = len(F2allline)minlen1 = min(len1,len2)for i in range(minlen1):print F1alllinei, F2alllineiif F1alllinei != F2alllinei:minlen2 = min(len(F1alllinei),len(F2alllinei)for j in range(minlen2):if F1alllineij != F2alllin

9、eij:print 'row is %d, column is %d' % (i+1,j+1)breakelse:continueelse:print 'they are equaln'97. 解析文件. Win32 用戶: 創(chuàng)建一個用來解析 Windows .ini 文件的程序. POSIX 用戶:創(chuàng)建一個解析 /etc/serves 文件的程序. 其它平臺用戶: 寫一個解析特定結(jié)構(gòu)的系統(tǒng)配置文件的程序.答案：這題沒看懂，抄的別人option = f = open(r'c:windowswin.ini')for line in f:if lin

10、e.startswith(''):continueif line.startswith(''):iterm = name = line1:line.rfind('')option.setdefault(name,iterm)continueif '=' in line:optionname.append(line.strip()print option98. 模塊研究. 提取模塊的屬性資料. 提示用戶輸入一個模塊名(或者從命令行接受輸入).然后使用 dir() 和其它內(nèi)建函數(shù)提取模塊的屬性, 顯示它們的名字, 類型, 值.答案：m

11、 = raw_input('Enter a module name: ')module = _import_(m)m1 = dir(module)print m1for i in m1:print 'name:',iprint 'tyoe:',type(getattr(module,i)print 'value:',getattr(module,i)print99. Python文檔字符串。進入Python標準庫所在的目錄。檢查每個 .py 文件看是否有_doc_ 字符串, 如果有, 對其格式進行適當?shù)恼須w類. 你的程序執(zhí)行完畢

12、后, 應該會生成一個漂亮的清單. 里邊列出哪些模塊有文檔字符串, 以及文檔字符串的內(nèi)容. 清單最后附上那些沒有文檔字符串模塊的名字.附加題: 提取標準庫中各模塊內(nèi)全部類(class)和函數(shù)的文檔.答案：這是入口#coding:utf-8import osimport sysnum = '''將所有路徑文件名全部提取出來'''def fun(dirName):for i in os.listdir(dirName):if os.path.isdir(dirName + "" + i):fun(dirName + '

13、9; + i)else:num.append(dirName + '' + i)fun(r'c:python27Lib')hasDoc = FalsestrTemp = ''fileobj1 = open('hasdoc.txt','a+')fileobj2 = open('nodoc.txt','a+')for i in num:print ifobj = open(i)for eachline in fobj:if (not hasDoc) and eachline.starts

14、with('"""'):hasDoc = Trueelif hasDoc and eachline.startswith('"""'):hasDoc = FalsestrTemp += eachlinebreakif hasDoc:strTemp += eachlineelse:breakif strTemp != "":fileobj1.write('filename: ' + i + 'n')fileobj1.write("_doc_&q

15、uot; + "n")fileobj1.write(strTemp + 'n')else:fileobj2.write('文件名：' + i + 'n')strTemp = ""fobj.close()fileobj1.close()fileobj2.close()9-10.家庭理財。創(chuàng)建一個家庭理財程序。你的程序需要處理儲蓄、支票、金融市場，定期存款等多種賬戶。為每種賬戶提供一個菜單操作界面，要有存款、取款、借、貸等操作。另外還要提供一個取消操作選項。用戶退出這個程序時相關(guān)數(shù)據(jù)應該保存到文件里取(出于備份

16、的目的，程序執(zhí)行過程中也要備份)。答案：太難了，不會。9-11.Web 站點地址.a) 編寫一個 URL 書簽管理程序. 使用基于文本的菜單, 用戶可以添加, 修改或者刪除書簽數(shù)據(jù)項. 書簽數(shù)據(jù)項中包含站點的名稱, URL 地址, 以及一行簡單說明(可選). 另外提供檢索功能,可以根據(jù)檢索關(guān)鍵字在站點名稱和 URL 兩部分查找可能的匹配. 程序退出時把數(shù)據(jù)保存到一個磁盤文件中去; 再次執(zhí)行時候加載保存的數(shù)據(jù).b)改進 a) 的解決方案, 把書簽輸出到一個合法且語法正確的 HTML 文件(.html 或 htm )中,這樣用戶就可以使用瀏覽器查看自己的書簽清單. 另外提供創(chuàng)建"文件夾&

17、quot;功能, 對相關(guān)的書簽進行分組管理.附加題: 請閱讀 Python 的 re 模塊了解有關(guān)正則表達式的資料, 使用正則表達式對用戶輸入的 URL 進行驗證.答案：不會做，參考自import re,osdef checkurl(url):regex = pile(r'(?:http|ftp)?:/' #http:/ or https:/r'(?:(?:A-Z0-9(?:A-Z0-90,61A-Z0-9)?.)+(?:A-Z2,6.?|A-Z0-9-2,.?)|'r'localhost' #localhostr'd1,3.d1,3.d

18、1,3.d1,3)'r'(?:d+)?'r'(?:/?|/?S+)$', re.IGNORECASE)if regex.match(url):return Trueelse:return Falsedef geturl():name = raw_input('pls input a url name: ')while 1:url = raw_input('pls input a url address: ')if checkurl(url):breakelse:print 'wrong url format, pl

19、s input again'mark = raw_input('pls input a url mark: ')folder = raw_input('pls input a url folder: ')return (name,url,mark,folder)def load(filename):f = open(filename,'a+')bmlist = f.readlines()f.close()return bmlistdef save(bmlist,filename):f = open(filename,'w+'

20、;)for line in bmlist:if len(line):continuef.write(line)f.close()def add(bmlist,name,url,mark,folder = 'default'):bookmark = ''bookmark = name + '' + url + '' + mark + '' + folder + os.linesepif bookmark not in bmlist:bmlist.append(bookmark)def modify(bmlist,in

21、dex,name,url,mark,folder):bookmark = ''bookmark = name + '' + url + '' + mark + '' + folder + os.linesepbmlistindex = bkdef delbm(bmlist,index):bmlist.pop(index)def findbk(bmlist,fname,furl):for i,item in enumerate(bmlist):(name,url,mark,folder) = item.split(''

22、;)if fname and furl:if (fname in name) and (furl in url):return iif fname and (fname in name):return iif furl and (furl in url):return ielse:return -1def output2html(bmlist):for i,item in enumerate(bmlist):(name,url,mark,folder) = item.split('')os.mkdir(folder.strip()filename = name.strip()

23、+ '.html'f = open(filename,'w+')fmt = '%dt%st<a href=%s>%s</a>t%st%s<br>'f.write('<html><head><title>bookmark</title></head><body>')content = fmt % (i+1,name,r'http:' + url,url,mark,folder)f.write(content)f

24、.write('</body></html>')f.close()os.rename(filename,folder.strip()+os.sep+filename)bmlist = load('url.txt')print bmlistwhile True:print '0. quit'print '1. add a url bookmark'print '2. modify a url bookmark'print '3. delete a url bookmark'pr

25、int '4. find a url bookmark'print '5. output url bookmark as html'print 'n'iInput = input('please input operation num: ')if(0 = iInput):save(bmlist,r'url.txt')breakelif (iInput<0 or iInput>5):print 'Error input operation,try again. 0 operation is qui

26、tn'continueelif 1 = iInput:data = geturl()add(bmlist,*data)print bmlistelif 2 = iInput:index = int(raw_input('bookmark index: ')data = geturl()modify(bmlist,index,*data)print bmlistelif 3 = iInput:index = int(raw_input('bookmark index: ')delbm(bmlist,index)print bmlistelif 4 = iI

27、nput:name = raw_input('url name: ')url = raw_input('url address: ')index = findbk(bmlist,name,url)if index = -1:print 'not found'else:print bmlistindexelif 5 = iInput:output2html(bmlist)9-12 用戶名和密碼?；仡櫨毩?-5，修改代碼使之可以支持“上次登錄時間”。請參閱time模塊中的文檔了解如何記錄用戶上次登錄的時間。另外提供一個系統(tǒng)管理員，他可以導出所有用戶的

28、用戶名，密碼（如需要可以加密），以及上次登錄時間。a）數(shù)據(jù)應保存在磁盤中，使用冒號：分隔，一次寫入一行，例如“Joe：boohoo：953176591.145，文件中數(shù)據(jù)的行數(shù)應該等于你系統(tǒng)上的用戶數(shù)。b）進一步改進你的程序，不再一次寫入一行，而使用pickle模塊保存整個數(shù)據(jù)對象。請參閱pickle模塊的文檔了解如何序列化/扁平化對象，以及如何讀寫保存的對象。一般來說，這個解決方案的代碼行數(shù)要比a）少；c）使用shelve模塊替換pickle模塊，由于可以省去一些維護代碼，這個解決方案的代碼比b）的更少。答案：from datetime import datetimeimport hashl

29、ib,osimport pickle as pimport shelve as sdb = def newuser():value = prompt = 'login name desired again: 'while True:name = raw_input(prompt).lower()if not name.isalnum() and '' in name:print 'name format error'continueelse:if db.has_key(name):prompt = 'name taken,try anot

30、her: 'continueelse:breakpwd = raw_input('login passwd desired: ')m = hashlib.md5()m.update(pwd)value.append(m.hexdigest()value.append(datetime.now()dbname = valueprint 'new user is %s, register time is %s' %(name,dbname1)def olduser():name = raw_input('login name desired agai

31、n: ').lower()pwd = raw_input('login passwd desired: ')m = hashlib.md5()m.update(pwd)passwd = db.get(name)if passwd0 = m.hexdigest():newtime = datetime.now()if (newtime - dbname1).days = 0 and (newtime - dbname1).seconds < 14400:print 'you already logged in at %s: ' %(dbname1)e

32、lse:passwd1 = newtimeprint 'welcome back %s, login time is %s' %(name,passwd1)else:print 'login incorrect'def removeuser():print dbname = raw_input('input a user name to remove: ').lower()if name in db:db.pop(name)else:print 'input error'def userlogin():while True:nam

33、e = raw_input('login name desired: ').lower()if not name.isalnum() and '' in name:print 'name format error'continueelse:if not db.has_key(name):print 'user name is not in db'answer = raw_input('register a new user? y/n').lower()if 'y' = answer:newuser(

34、)breakelif 'n' = answer:breakelse:print 'user name is already in db'olduser()breakdef outputA():print dbf = open('account.txt','w')for key in db:user = key + ':' + dbkey0 + ':' + str(dbkey1) + os.linesepf.write(user)f.close()def outputB():accountfile =

35、 'pickle.data'f = open(accountfile,'w')p.dump(db,f)f.close()f = open(accountfile)accountdb = p.load(f)print accountdbdef outputC():accountfile = 'shelve.data'accountdb = s.open(accountfile,'c')accountdb'data' = dbaccount.close()accountdb = s.open(accountfile,&

36、#39;r')print accountdb'data'def adminlogin():while True:name = raw_input('login name desired: ').lower()if not name.isalnum() and '' in name:print 'name format error'continueelse:pwd = raw_input('login passwd desired: ')if name = 'root' and pwd = &

37、#39;root':print 'welcome admin'breakelse:print 'user name or passwd is wrong,input again'if len(db) = 0:print 'there is nothing you can do'else:answer = raw_input('output all account? y/n').lower()if 'y' = answer:outputC()elif 'n' = answer:print &#

38、39;bye'def showmenu():prompt = '''(A)dmin login(U)ser login(R)emove a existing user(Q)uitEnter choice: '''done = Falsewhile not done:chosen = Falsewhile not chosen:try:choice = raw_input(prompt).strip()0.lower()except (EOFError,keyboardInterrupt):choice = 'q'print

39、 'nYou picked: %s' % choiceif choice not in 'aurq':print 'invalid option.try again'else:chosen = Trueif choice = 'q':done = Trueif choice = 'r':removeuser()if choice = 'u':userlogin()if choice = 'a':adminlogin()if _name_ = '_main_':show

40、menu()913. 命令行參數(shù)a) 什么是命令行參數(shù), 它們有什么用?b) 寫一個程序, 打印出所有的命令行參數(shù)。答案：a)命令行參數(shù)是調(diào)用某個程序時除程序名以外的其他參數(shù)。命令行參數(shù)使程序員在啟動一個程序時對程序行為作出選擇。b)import sysprint str(sys.argv)9-14 記錄結(jié)果。修改你的計算器程序（練習5-6）使之接受命令行參數(shù)。例如$ calc.py 1 + 2 只輸出計算結(jié)果。另外，把每個表達式和它的結(jié)果寫入到一個磁盤文件中，當使用下面的命令時 $ calc.py print 會把記錄的內(nèi)容顯示到屏幕上，然后重置文件。這里是樣例展示：$ calc.py 1

41、+ 23$ calc.py 3 327$ calc.py print1 + 233 327$ calc.py print$ 答案：#coding:utf-8import sys,osdef calculator(expression):operator = '+','-','*','/','%','*'sysmol = ''for i in operator:if i in sys.argv:sysmol = iif sysmol = '':print '操作

42、符錯誤'returnnum = expression.split(sysmol)if '.' in num0 or '.' in num1:num1 = float(num0)num2 = float(num1)else:num1 = int(num0)num2 = int(num1)f = open('test.txt','a+')f.write(expression)if sysmol = operator0:result = str(num1 + num2) + os.linesepprint result,f.wr

43、ite(result)elif sysmol = operator1:result = str(num1 - num2) + os.linesepprint result,f.write(result)elif sysmol = operator2:result = str(num1 * num2) + os.linesepprint result,f.write(result)elif sysmol = operator3:result = str(num1 / num2) + os.linesepprint result,f.write(result)elif sysmol = opera

44、tor4:result = str(num1 % num2) + os.linesepprint result,f.write(result)elif sysmol = operator5:result = str(num1 * num2) + os.linesepprint result,f.write(result)if sys.argv1 = 'print':if os.path.exists(r'test.txt'):f = open('test.txt','r')for line in f:print line,f.cl

45、ose()else:print 'file not exist.'else:expression = str(sys.argv1 + ' ' + sys.argv2 + ' ' + sys.argv3+ os.linesep)calculator(expression)915. 復制文件. 提示輸入兩個文件名(或者使用命令行參數(shù)). 把第一個文件的內(nèi)容復制到第二個文件中去.答案：import sysfile1 = sys.argv1file2 = sys.argv2f1 = open(file1,'r')f2 = open(fil

46、e2,'a+')f2.write('n')for line in f1:f2.write(line)f1.close()f2.close()916. 文本處理。人們輸入的文字常常超過屏幕的最大寬度。編寫一個程序， 在一個文本文件中查找長度大于 80 個字符的文本行。從最接近 80 個字符的單詞斷行，把剩余文件插入到下一行處.程序執(zhí)行完畢后，應該沒有超過 80 個字符的文本行了。答案：這個基本能達到要求，不過最后一行會少個字符或結(jié)尾符號，因為最后一行沒有換行符file = open('test1.txt','r')list1 = f

47、or line in file:symbol = Truewhile symbol:if len(line) <= 80:list1.append(line:-1)symbol = Falseelse:count = len(line)/80for i in range(count):list1.append(line:81)line = line81:print list1file1 = open('test2.txt','a+')for i in list1:file1.write(i)file1.write('n')方法二：file

48、= open('test1.txt','r')list1 = for line in file:symbol = Truewhile symbol:if len(line) <= 80:list1.append(line)symbol = Falseelse:list1.append(line:81)line = line81:print list1file1 = open('test2.txt','a+')for i in list1:if i.endswith('n'):i = i:-1file1.wri

49、te(i)file1.write('n')917. 文本處理。創(chuàng)建一個原始的文本文件編輯器。你的程序應該是菜單驅(qū)動的，有如下這些選項：1) 創(chuàng)建文件(提示輸入文件名和任意行的文本輸入)；2) 顯示文件(把文件的內(nèi)容顯示到屏幕)；3) 編輯文件(提示輸入要修改的行， 然后讓用戶進行修改)；4) 保存文件；5) 退出.答案：這里把3編輯文件和4保存文件合并在一起了import osdef newfile():symbol = Truewhile symbol:filename = raw_input('Enter a filename: ')if os.path.e

50、xists(filename):print 'file is exists.'else:symbol1 = Truewhile symbol1:content = raw_input('Enter content("q" for quit): ')if content = 'q':breakf1 = open(filename,'a+')f1.write(content)f1.write('n')f1.close()symbol = Falsedef showfile():symbol = Tr

51、uewhile symbol:filename = raw_input('Enter a filename: ')if not os.path.exists(filename):print 'file is not exists.'else:f1 = open(filename,'r')for line in f1:print line,f1.close()breakdef editfile():symbol = Truewhile symbol:filename = raw_input('Enter a filename: ')

52、if not os.path.exists(filename):print 'file is not exists.'else:index = int(raw_input('edit index of line: ')con = raw_input('Enter edit content: ')ls = f = open(filename,'r')ls = f.readlines()f.close()lsindex - 1 = con + os.linesepf1 = open(filename,'w')for l

53、ine in ls:f1.write(line)f1.close()symbol = Falsedef showmenu():prompt = '''Menu:(N)ewfile(S)howfile(E)ditfile(Q)uitEnter choice: '''done = Truewhile done:chosen = Truewhile chosen:try:choice = raw_input(prompt).strip()0.lower()except (EOFError,KeyboardInterrupt):choice = '

54、;q'print 'nYou picked: %s' % choiceif choice not in 'ncesq':print 'invalid option, try again'else:chosen = Falseif choice = 'q':breakif choice = 'n':newfile()if choice = 's':showfile()if choice = 'e':editfile()if _name_ = '_main_':s

55、howmenu()918. 搜索文件. 提示輸入一個字節(jié)值(0 - 255)和一個文件名. 顯示該字符在文件中出現(xiàn)的次數(shù)。答案：num = int(raw_input('Enter a number between 0 255: ')filename = raw_input('Enter filename: ')ch = chr(num)numcount = 0f = open(filename,'r')for line in f:numcount += line.count(ch)print numcount919. 創(chuàng)建文件。創(chuàng)建前一個問題的

56、輔助程序。創(chuàng)建一個隨機字節(jié)的二進制數(shù)據(jù)文件，但某一特定字節(jié)會在文件中出現(xiàn)指定的次數(shù)。該程序接受三個參數(shù)：1) 一個字節(jié)值( 0 - 255 )；2) 該字符在數(shù)據(jù)文件中出現(xiàn)的次數(shù)；3) 數(shù)據(jù)文件的總字節(jié)長度。你的工作就是生成這個文件，把給定的字節(jié)隨機散布在文件里，并且要求保證給定字符在文件中只出現(xiàn)指定的次數(shù)，文件應精確地達到要求的長度。答案：import randomdef abc(num, count, len):l = n = len - countfor i in range(n):randomnum = random.randint(0,255)symbol = Truewhile s

57、ymbol:if randomnum = num:randomnum = random.randint(0,255)else:l.append(randomnum)symbol = Falsefor i in range(count):l.append(num)random.shuffle(l)print lf = open('test.txt','w')f.close()for i in l:f = open('test.txt','a+')f.write('%08d %d' % (int(bin(i)2:),i)f.write('n')f.close()print '%08d %d' % (int(bin(i)2:),i)abc(66,5,20)920.壓縮文件。寫一小段代碼，壓縮/解壓縮gzip或bzip格式的文件。可以使用命令行下的gzip或bzip2以及GUI程序Po