python 核心编程课后练习(chapter 3)

3-8

 #3-8
 "makeTextFile.py -- create text file"

 import os
 ls = os.linesep

 #get filename
 fname = raw_input()
 while True:

   if os.path.exists(fname):
     print "ERROR: '%s' already exists" % fname
   else:
     break
 all = []
 print "\nEnter lines ('.' by itself to quit).\n"      

 while True:
   entry = raw_input('newline:')
   if entry == '.':
     break
   else:
     all.append(entry)

 fobj = open(fname, 'w')
 fobj.writelines(['%s%s' % (x, ls) for x in all])
 fobj.close()
 print "DONE!" 

3-10

 #3-10
 "readtextFile.py---read and display text"
 import os

 fname = raw_input("Enter file name:")
 print

 if os.path.exists(fname):
   fobj = open(fname, 'r')
   for eachline in fobj:
     print eachline.strip()
   fobj.close()
 else:
   print "file not exists!!"  

 #3-11
 "readtextFile.py---read and display text"

 fname = raw_input("Enter file name:")
 print

 try:
   fobj = open(fname, 'r')
 except IOError, e:
   print "*** file open error: ", e
 else:
   for eachline in fobj:
     print eachline.strip()
   fobj.close()  

3-12

 #3-12
 "readtextFile.py---read and display text"
 import os
 ls = os.linesep

 print """Enter your option:
 (w)create a file
 (r)read a file
 (others)exit
 """

 def WriteFile(str):
   all = []
   if os.path.exists(str):
     print "ERROR: '%s' already exists" % fname
     return

   print "\nEnter lines ('.' by itself to quit).\n"
   while True:
       entry = raw_input('newline:')
       if entry == '.':
         break
       else:
         all.append(entry)

     fobj = open(fname, 'w')
     fobj.writelines(['%s%s' % (x, ls) for x in all])
     fobj.close()
     print "DONE!" 

 def ReadFile(str):
   #fname = raw_input("Enter file name:")
   print

   if os.path.exists(str):
       fobj = open(str, 'r')
       for eachline in fobj:
         print eachline.strip()
       fobj.close()
   else:
       print "file not exists!!" 

 opt =raw_input("your option is:")

 if(opt == 'w'):
   fname = raw_input("the file to write is: ")
   WriteFile(fname)
 elif opt== 'r':
   fname = raw_input("the file to read is: ")
   ReadFile(fname)
 else:
   print "exit" 

3-13

 #3-13
 "readtextFile.py---read and display text"
 import os
 ls = os.linesep

 print """Enter your option:
 (w)create a file
 (r)read a file
 (m)modify a file
 (others)exit
 """

 def WriteFile(str):
   all = []
   if os.path.exists(str):
     print "ERROR: '%s' already exists" % fname
     return

   print "\nEnter lines ('.' by itself to quit).\n"
   while True:
       entry = raw_input('newline:')
       if entry == '.':
         break
       else:
         all.append(entry)

     fobj = open(fname, 'w')
     fobj.writelines(['%s%s' % (x, ls) for x in all])
     fobj.close()
     print "DONE!" 

 def ReadFile(str):
   #fname = raw_input("Enter file name:")
   print

   if os.path.exists(str):
       fobj = open(str, 'r')
       for eachline in fobj:
         print eachline.strip()
       fobj.close()
   else:
       print "file not exists!!" 

 def ModifyFile(str):
   all = []
   if os.path.exists(str):
     i = 1
     fobj = open(str, 'r')
     for eachline in fobj:
       newline = eachline.strip()
       print "line %d: %s" % (i,newline)
       newline = raw_input("replace with:")
       all.append(newline)
       i+=1
     fobj.close()

     opt = raw_input("do you want to save your changes,\ny(yes) \nother(n):")
     if opt == 'y':
       output = open(str, 'w')
       output.writelines(['%s%s' % (x, ls) for x in all])
       output.close()
     else:
       return
   else:
     print "file not exists!!"       

 opt =raw_input("your option is:")

 if(opt == 'w'):
   fname = raw_input("the file to write is: ")
   WriteFile(fname)
 elif opt== 'r':
   fname = raw_input("the file to read is: ")
   ReadFile(fname)
 elif opt == 'm':
   fname = raw_input("the file to modify is:")
   ModifyFile(fname)
   print "the new file content is:"
   ReadFile(fname)
 else:
   print "exit"