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

2、_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 = open(f,r)sum = 0for i in f1:sum += 1print sumf = raw_input(Enter filename :)f1 = open(f,r

3、)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()su

4、m = 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_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 = ope

5、n(test1.txt,r)scores = for i in f:if 0 = int(i.strip()= 100:scores.append(int(i.strip()else:print score wrong ,please againif 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:print score is

6、 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 = F1.readlines()F2allline = F2.readlines()F1.close()F2.close()len1 = len(F1

7、allline)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 != F2alllineij:print row is %d, column is %d % (i+1,j+1)breakelse:continueelse:prin

8、t they are equaln97. 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(rc:windowswin.ini)for line in f:if line.startswith(;):continueif line.startswith():iterm = name = line1:line.rfind()option.setdefault(name,i

9、term)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 = 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)pri

10、nt 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)行完畢后, 應(yīng)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 i

11、n os.listdir(dirName):if os.path.isdir(dirName + + i):fun(dirName + + i)else:num.append(dirName + + i)fun(rc: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.startswith()

12、:hasDoc = Trueelif hasDoc and eachline.startswith():hasDoc = FalsestrTemp += eachlinebreakif hasDoc:strTemp += eachlineelse:breakif strTemp != :fileobj1.write(filename: + i + n)fileobj1.write(_doc_ + n)fileobj1.write(strTemp + n)else:fileobj2.write(文件名： + i + n)strTemp = fobj.close()fileobj1.close()

13、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(yīng)該保存到文件里取(出于備份的目的，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

14、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(?

15、:(?:A-Z0-9(?:A-Z0-90,61A-Z0-9)?.)+(?:A-Z2,6.?|A-Z0-9-2,.?)|rlocalhost #localhostrd1,3.d1,3.d1,3.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

16、(url):breakelse:print wrong url format, pls input againmark = 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+)f

17、or 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,index,name,url,mark,folder):bookmark = bookmark = na

18、me + ; + 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(;)if fname and furl:if (fname in name) and (furl in url):return iif fname and (fname in name):re

19、turn 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() + .htmlf = open(filename,w+)fmt = %dt%st%st%st%sf.write(bookmark)content = fmt % (i+1,name,rhttp: + url,u

20、rl,mark,folder)f.write(content)f.write()f.close()os.rename(filename,folder.strip()+os.sep+filename)bmlist = load(url.txt)print bmlistwhile True:print 0. quitprint 1. add a url bookmarkprint 2. modify a url bookmarkprint 3. delete a url bookmarkprint 4. find a url bookmarkprint 5. output url bookmark

21、 as htmlprint niInput = input(please input operation num: )if(0 = iInput):save(bmlist,rurl.txt)breakelif (iInput5):print Error input operation,try again. 0 operation is quitncontinueelif 1 = iInput:data = geturl()add(bmlist,*data)print bmlistelif 2 = iInput:index = int(raw_input(bookmark index: )dat

22、a = geturl()modify(bmlist,index,*data)print bmlistelif 3 = iInput:index = int(raw_input(bookmark index: )delbm(bmlist,index)print bmlistelif 4 = iInput:name = raw_input(url name: )url = raw_input(url address: )index = findbk(bmlist,name,url)if index = -1:print not foundelse:print bmlistindexelif 5 =

23、 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(dǎo)出所有用戶的用戶名，密碼（如需要可以加密），以及上次登錄時間。a）數(shù)據(jù)應(yīng)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(yīng)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

24、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 hashlib,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:pri

25、nt name format errorcontinueelse:if db.has_key(name):prompt = name taken,try another: 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

26、 olduser():name = raw_input(login name desired again: ).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 i

27、n at %s: %(dbname1)else:passwd1 = newtimeprint welcome back %s, login time is %s %(name,passwd1)else:print login incorrectdef removeuser():print dbname = raw_input(input a user name to remove: ).lower()if name in db:db.pop(name)else:print input errordef userlogin():while True:name = raw_input(login

28、name desired: ).lower()if not name.isalnum() and in name:print name format errorcontinueelse:if not db.has_key(name):print user name is not in dbanswer = raw_input(register a new user? y/n).lower()if y = answer:newuser()breakelif n = answer:breakelse:print user name is already in dbolduser()breakdef

29、 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 = pickle.dataf = open(accountfile,w)p.dump(db,f)f.close()f = open(accountfile)accountdb = p.load(f)print accountdbdef outputC():accountfile =

30、shelve.dataaccountdb = s.open(accountfile,c)accountdbdata = dbaccount.close()accountdb = s.open(accountfile,r)print accountdbdatadef adminlogin():while True:name = raw_input(login name desired: ).lower()if not name.isalnum() and in name:print name format errorcontinueelse:pwd = raw_input(login passw

31、d desired: )if name = root and pwd = root:print welcome adminbreakelse:print user name or passwd is wrong,input againif len(db) = 0:print there is nothing you can doelse:answer = raw_input(output all account? y/n).lower()if y = answer:outputC()elif n = answer:print byedef showmenu():prompt = (A)dmin

32、 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 = qprint nYou picked: %s % choiceif choice not in aurq:print invalid option.try againelse:

33、chosen = Trueif choice = q:done = Trueif choice = r:removeuser()if choice = u:userlogin()if choice = a:adminlogin()if _name_ = _main_:showmenu()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

34、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 + 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 oper

35、ator:if i in sys.argv:sysmol = iif sysmol = :print 操作符錯誤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 res

36、ult,f.write(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

37、 = operator4: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(rtest.txt):f = open(test.txt,r)for line in f:print line,f.close()else:print file not exist.e

38、lse:expression = str(sys.argv1 + + sys.argv2 + + sys.argv3+ os.linesep)calculator(expression)915. 復(fù)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(fù)制到第二個文件中去.答案：import sysfile1 = sys.argv1file2 = sys.argv2f1 = open(file1,r)f2 = open(file2,a+)f2.write(n)for line in f1:f2.write(line)f1.close()f2.close()916. 文本處理。

39、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(yīng)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 = for line in file:symbol = Truewhile symbol:if len(line) = 80:list1.append(line:-1)symbol = Falseelse:count = len(line

40、)/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 = 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

41、 = line81:print list1file1 = open(test2.txt,a+)for i in list1:if i.endswith(n):i = i:-1file1.write(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(yīng)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():sy

42、mbol = Truewhile symbol:filename = raw_input(Enter a filename: )if os.path.exists(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

43、():symbol = Truewhile 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: )if not os.path.exists(file

44、name):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 line in ls:f1.write(line)f1.close()symbol = Falsedef showmenu():prompt = Menu

45、:(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 = qprint nYou picked: %s % choiceif choice not in ncesq:print invalid option, try againelse:chosen = Falseif cho

46、ice = q:breakif choice = n:newfile()if choice = s:showfile()if choice = e:editfile()if _name_ = _main_:showmenu()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,

47、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(yīng)精確地達到要求的長度。答案：import randomdef abc(num, count, len):l = n = len - co

48、untfor i in range(n):randomnum = random.randint(0,255)symbol = Truewhile symbol: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PowerArchiver，StuffIt，或WinZip來確認你的Pyt