python核心编程第二版第9章习题答案.docx

91. 文件过滤. 显示一个文件的所有行, 忽略以井号( # )开头的行. 这个字符被用做Python , Perl, Tcl, 等大多脚本文件的注释符号.附加题: 处理不是第一个字符开头的注释.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. 文件访问. 提示输入数字 N 和文件 F, 然后显示文件 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. 提示输入一个文件名, 然后显示这个文本文件的总行数.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)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. 文件访问. 写一个逐页显示文本文件的程序. 提示输入一个文件名, 每次显示文本文件的 25 行, 暂停并向用户提示按任意键继续., 按键后继续执行.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_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 考试成绩，改进你的考试成绩问题（练习5-3和6-4），要求能从多个文件中读入考试成绩。文件的数据格式由你自己决定。答案：f = open(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 A,if.close()print average score is %.2f % (sum(scores)/len(scores)96. 文件比较. 写一个比较两个文本文件的程序. 如果不同, 给出第一个不同处的行号和列号.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(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 != F2alllineij:print row is %d, column is %d % (i+1,j+1)breakelse:continueelse:print they are equaln97. 解析文件. Win32 用户: 创建一个用来解析 Windows .ini 文件的程序. POSIX 用户:创建一个解析 /etc/serves 文件的程序. 其它平台用户: 写一个解析特定结构的系统配置文件的程序.答案：这题没看懂，抄的别人option = f = open(rc:windowswin.ini)for line in f:if line.startswith(;):continueif line.startswith():iterm = name = line1:line.rfind()option.setdefault(name,iterm)continueif = in line:optionname.append(line.strip()print option98. 模块研究. 提取模块的属性资料. 提示用户输入一个模块名(或者从命令行接受输入).然后使用 dir() 和其它内建函数提取模块的属性, 显示它们的名字, 类型, 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)print value:,getattr(module,i)print99. Python文档字符串。进入Python标准库所在的目录。检查每个 .py 文件看是否有_doc_ 字符串, 如果有, 对其格式进行适当的整理归类. 你的程序执行完毕后, 应该会生成一个漂亮的清单. 里边列出哪些模块有文档字符串, 以及文档字符串的内容. 清单最后附上那些没有文档字符串模块的名字.附加题: 提取标准库中各模块内全部类(class)和函数的文档.答案：这是入口#coding:utf-8import osimport sysnum = 将所有路径文件名全部提取出来def fun(dirName):for i in 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():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()fileobj2.close()9-10.家庭理财。创建一个家庭理财程序。你的程序需要处理储蓄、支票、金融市场，定期存款等多种账户。为每种账户提供一个菜单操作界面，要有存款、取款、借、贷等操作。另外还要提供一个取消操作选项。用户退出这个程序时相关数据应该保存到文件里取(出于备份的目的，程序执行过程中也要备份)。答案：太难了，不会。9-11.Web 站点地址.a) 编写一个 URL 书签管理程序. 使用基于文本的菜单, 用户可以添加, 修改或者删除书签数据项. 书签数据项中包含站点的名称, URL 地址, 以及一行简单说明(可选). 另外提供检索功能,可以根据检索关键字在站点名称和 URL 两部分查找可能的匹配. 程序退出时把数据保存到一个磁盘文件中去; 再次执行时候加载保存的数据.b)改进 a) 的解决方案, 把书签输出到一个合法且语法正确的 HTML 文件(.html 或 htm )中,这样用户就可以使用浏览器查看自己的书签清单. 另外提供创建文件夹功能, 对相关的书签进行分组管理.附加题: 请阅读 Python 的 re 模块了解有关正则表达式的资料, 使用正则表达式对用户输入的 URL 进行验证.答案：不会做，参考自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,.?)|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(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+)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,index,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(;)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() + .htmlf = open(filename,w+)fmt = %dt%st%st%st%sf.write(bookmark)content = fmt % (i+1,name,rhttp: + url,url,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 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: )data = 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 = iInput:output2html(bmlist)9-12 用户名和密码。回顾练习7-5，修改代码使之可以支持“上次登录时间”。请参阅time模块中的文档了解如何记录用户上次登录的时间。另外提供一个系统管理员，他可以导出所有用户的用户名，密码（如需要可以加密），以及上次登录时间。a）数据应保存在磁盘中，使用冒号：分隔，一次写入一行，例如“Joe：boohoo：953176591.145，文件中数据的行数应该等于你系统上的用户数。b）进一步改进你的程序，不再一次写入一行，而使用pickle模块保存整个数据对象。请参阅pickle模块的文档了解如何序列化/扁平化对象，以及如何读写保存的对象。一般来说，这个解决方案的代码行数要比a）少；c）使用shelve模块替换pickle模块，由于可以省去一些维护代码，这个解决方案的代码比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:print 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 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 in 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 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 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 = 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 passwd 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 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:chosen = Trueif choice = q:done = Trueif choice = r:removeuser()if choice = u:userlogin()if choice = a:adminlogin()if _name_ = _main_:showmenu()913. 命令行参数a) 什么是命令行参数, 它们有什么用?b) 写一个程序, 打印出所有的命令行参数。答案：a)命令行参数是调用某个程序时除程序名以外的其他参数。命令行参数使程序员在启动一个程序时对程序行为作出选择。b)import sysprint str(sys.argv)9-14 记录结果。修改你的计算器程序（练习5-6）使之接受命令行参数。例如$ calc.py 1 + 2 只输出计算结果。另外，把每个表达式和它的结果写入到一个磁盘文件中，当使用下面的命令时 $ calc.py print 会把记录的内容显示到屏幕上，然后重置文件。这里是样例展示：$ 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 operator:if i in sys.argv:sysmol = iif sysmol = :print 操作符错误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.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 = 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.else:expression = str(sys.argv1 + + sys.argv2 + + sys.argv3+ os.linesep)calculator(expression)915. 复制文件. 提示输入两个文件名(或者使用命令行参数). 把第一个文件的内容复制到第二个文件中去.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. 文本处理。人们输入的文字常常超过屏幕的最大宽度。编写一个程序， 在一个文本文件中查找长度大于 80 个字符的文本行。从最接近 80 个字符的单词断行，把剩余文件插入到下一行处.程序执行完毕后，应该没有超过 80 个字符的文本行了。答案：这个基本能达到要求，不过最后一行会少个字符或结尾符号，因为最后一行没有换行符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)/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 = line81:print list1file1 = open(test2.txt,a+)for i in list1:if i.endswith(n):i = i:-1file1.write(i)file1.write(n)917. 文本处理。创建一个原始的文本文件编辑器。你的程序应该是菜单驱动的，有如下这些选项：1) 创建文件(提示输入文件名和任意行的文本输入)；2) 显示文件(把文件的内容显示到屏幕)；3) 编辑文件(提示输入要修改的行， 然后让用户进行修改)；4) 保存文件；5) 退出.答案：这里把3编辑文件和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.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():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(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 line 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 = qprint nYou picked: %s % choiceif choice not in ncesq:print invalid option, try againelse:chosen = Falseif choice = q:breakif choice = n:newfile()if choice = s:showfile()if choice = e:editfile()if _name_ = _main_:showmenu()918. 搜索文件. 提示输入一个字节值(0 - 255)和一个文件名. 显示该字符在文件中出现的次数。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. 创建文件。创建前一个问题的辅助程序。创建一个随机字节的二进制数据文件，但某一特定字节会在文件中出现指定的次数。该程序接受三个参数：1) 一个字节值( 0 - 255 )；2) 该字符在数据文件中出现的次数；3) 数据文件的总字节长度。你的工作就是生成这个文件，把给定的字节随机散布在文件里，并且要求保证给定字符在文件中只出现指定的次数，文件应精确地达到要求的长度。答案：import randomdef abc(num, count, len):l = n = len - countfor 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.压缩文件。写一小段代码，压缩/解压缩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来确认你的Python支持这两个库