There is some prolem in the funciton modification below. Please checkit and tell me what is worng?

Discussion in 'C++' started by Unpopular, Feb 13, 2008.

  1. Unpopular

    Unpopular Guest

    void directory::modification()//???????????
    {
    clrscr();

    cout<< "\n\t @@@@@@ @@@@@ @@@@@ @@@@@@ @@@@@ @ @
    @@@@@@ ";
    cout<< "\n\t=====@ @ @ @ @ @ @@ @
    @ =====";
    cout<< "\n\t=====@@@@@@ @ @ @ @ @ @ @ @ @
    @@@ =====";
    cout<< "\n\t=====@ @ @ @ @ @ @ @@
    @ @ =====";
    cout<< "\n\t @@@@@@ @@@@@ @@@@@ @ @@@@@ @ @
    @@@@@@ \n\n\n\n";
    cout<<"I am inside the modification function before opening of
    addressesFiile.";
    getch();
    long pn;
    int n,i;
    ifstream inFile;
    ofstream outFile;

    inFile.open("addressesFile");
    if(!inFile)
    {
    cout<<"\nI am inside the modification function after opening
    of addressesFiile. Checking now with if";
    getch();
    cout<<"\n File not found!";
    outFile.close();
    exit(-1);
    }
    outFile.open("new");
    cout<<"\nI am inside the modification function after just creating
    new";
    getch();
    n=test();
    if(n==0)
    {
    cout<<"\nI am inside the modification function. new is
    empty";
    getch();
    cout<<"\n The file is empty. ! ";
    getch();
    return;
    }
    cout<<"\nI am inside the modification function before entering the
    while loop.";
    getch();
    int deleteMe = 0;
    while(inFile.good())
    {

    inFile.read((char*)&obj,sizeof(obj));
    outFile.write((char*)&obj,sizeof(obj));
    cout<<"\nI am inside the modification function inside the while
    loop and I have finished round "<<deleteMe+1;
    deleteMe = deleteMe + 1;
    getch();
    }
    cout<<"\nI am inside the modification function just outside
    the while loop.";
    inFile.close();
    outFile.close();
    outFile.open("addressesFile",ios::trunc);
    inFile.open("new");
    if(inFile.fail())
    {
    cout<<"\n Sorry! File not found !";
    exit(-1);
    }
    char ch;
    cout<<"\n Enter the Land Line Phone Number or the Contact :";
    cin>>pn;
    ch=cin.get();
    cin.get(ch);
    for(i=0;i<n;i++)
    {
    inFile.read((char*)&obj,sizeof(obj));
    char d;
    if(pn==landLinePhone)
    {
    //view1();
    cout<<" Name : "<<obj.contactName<<"\n";
    cout<<" Home Address : "<<obj.homeAddress<<"\n";
    cout<<" EMAIL ADDRESS : "<<obj.email<<"\n";
    cout<<" Cellular Phone Nmber : "<<obj.cellularPhone<<"\n";
    cout<<" Land Line Phone Number : "<<obj.landLinePhone<<"\n
    \n";

    d=check("HOUSE PHONE NUMBER ");
    if((d=='y') || (d=='Y'))
    {
    cout<<"\n Enter the new land line phone number of the
    contact, please. :";
    cin>>landLinePhone;
    ch=cin.get();
    cin.get(ch);
    }
    if(check("OFFICE PHONE NUMBER ")=='Y')
    {
    cout<<"\n Enter the new cellular phone number of the
    contact, please. :";
    cin>>cellularPhone;
    ch=cin.get();
    cin.get(ch);
    }
    if(check("Name of the Contact")=='y')
    {
    cout<<"\n Enter the name of the contact, please. : ";
    cin.getline(contactName,20,'\n');
    }
    if(check("HOME ADDRESS")=='y')
    {
    cout<<"\n Enter the new Home Address of the contact,
    please. :";
    cin.getline(homeAddress,50,'\n');
    }
    if(check("EMAIL ADDRESS:")=='y')
    {
    cout<<"\n Enter the new E-mail Address of the contact,
    please. :";
    cin.getline(email,25,'\n');
    }
    }//the outer if ends here.
    outFile.write((char*)&obj,sizeof(obj));
    }
    outFile.close();
    inFile.close();
    }
     
    Unpopular, Feb 13, 2008
    #1
    1. Advertising

  2. Re: There is some prolem in the funciton modification below. Pleasecheck it and tell me what is worng?

    `Some problem' is rather vague. Anyway, here are some brief notes on
    `what's wrong':

    Unpopular wrote:
    > void directory::modification()//???????????
    > {

    [...] -- many noisy lines ommited here and below
    > inFile.open("addressesFile");
    > outFile.open("new");


    I'd guess, that file "new" is now empty and locked for writing in text mode.

    > n=test();

    Hu?? What happens in test()?

    > if(n==0)
    > {
    > cout<<"\n The file is empty. ! ";
    > getch();
    > return;

    Of course "new" is empty! So bye bye here?
    > }


    > while(inFile.good())
    > {

    So let's do some _binary_ I/O on _text_ files -- good luck!
    > inFile.read((char*)&obj,sizeof(obj));
    > outFile.write((char*)&obj,sizeof(obj));

    What is obj? There are _very_ strong restrinctions, if you want to use
    it like that!
    > }


    > inFile.close();
    > outFile.close();
    > outFile.open("addressesFile",ios::trunc);
    > inFile.open("new");


    > for(i=0;i<n;i++)

    Hu, what's n? Ahh, I see, the result of your test() above -- weird.

    > {

    And again, binary I/O on a text file, using undefined `obj':
    > inFile.read((char*)&obj,sizeof(obj));

    Only cowards check return values -- real programmers post in c.l.c++ :)

    > if(pn==landLinePhone)

    What's landLinePhone? Did you mean obj.landLinePhone?
    > {
    > cout<<" Name : "<<obj.contactName<<"\n";
    > cout<<" Home Address : "<<obj.homeAddress<<"\n";
    > cout<<" EMAIL ADDRESS : "<<obj.email<<"\n";
    > cout<<" Cellular Phone Nmber : "<<obj.cellularPhone<<"\n";
    > cout<<" Land Line Phone Number : "<<obj.landLinePhone<<"\n

    Ever thought of providing a suitable operator <<()? Then you may write
    cout << obj;

    > d=check("HOUSE PHONE NUMBER ");

    check()? Sorry, but I'm getting tired now.

    I think, switching to binary file mode will fix one of your `some problem'.
    But you should improve your coding style. And if you need more help,
    you'll have to post code, that compiles and runs.

    -- ralph
     
    Ralph D. Ungermann, Feb 14, 2008
    #2
    1. Advertising

  3. Unpopular

    James Kanze Guest

    Re: There is some prolem in the funciton modification below. Pleasecheck it and tell me what is worng?

    On Feb 14, 1:13 pm, "Ralph D. Ungermann" <>
    wrote:
    > `Some problem' is rather vague. Anyway, here are some brief notes on
    > `what's wrong':


    > Unpopular wrote:
    > > void directory::modification()//???????????
    > > {
    > > inFile.open("addressesFile");
    > > outFile.open("new");


    > I'd guess, that file "new" is now empty and locked for writing
    > in text mode.


    First, until you test the status of outFile, you don't know
    whether the open succeeded or not. If it didn't succeed, you
    can't say anything about the file "new". If it did succeed,
    then their is an empty file by that name---if the file existed
    beforehand, you've emptied it, and if it didn't, you've created
    it. (That's what the standard requires.) I can't see why it
    would be locked, however.

    > > while(inFile.good())


    And of course, this is NOT the way to read a file.

    (I didn't even look at the code in the original posting; it was
    too big and too much of a mess to be bothered with. So I don't
    really know what the OP was trying to do. But looping on
    "inFile.good()" is never correct.)

    > > {


    > So let's do some _binary_ I/O on _text_ files -- good luck!
    > > inFile.read((char*)&obj,sizeof(obj));
    > > outFile.write((char*)&obj,sizeof(obj));


    > What is obj? There are _very_ strong restrinctions, if you want to use
    > it like that!


    Like: it must be an array of characters (char or unsigned char).
    The cast in question is a reinterpret_cast, and any time you
    need a reinterpret_cast, you should ask yourself questions.
    (Although if all he does is then write it with write(), it
    almost certainly doesn't matter, since read will read it as an
    array of characters, and write will write it as an array of
    characters. But then, why isn't it defined as an array of
    characters?)

    And of course, as you point out, if you really want to do binary
    I/O, you need to open the files in mode binary, and imbue the
    "C" locale.

    --
    James Kanze (GABI Software) email:
    Conseils en informatique orientée objet/
    Beratung in objektorientierter Datenverarbeitung
    9 place Sémard, 78210 St.-Cyr-l'École, France, +33 (0)1 30 23 00 34
     
    James Kanze, Feb 15, 2008
    #3
    1. Advertising

Want to reply to this thread or ask your own question?

It takes just 2 minutes to sign up (and it's free!). Just click the sign up button to choose a username and then you can ask your own questions on the forum.
Similar Threads
  1. manish
    Replies:
    1
    Views:
    324
    Christopher Benson-Manica
    Apr 2, 2004
  2. fastwings
    Replies:
    3
    Views:
    4,146
    Rolf Magnus
    Apr 17, 2004
  3. wcc
    Replies:
    3
    Views:
    272
    Terry Reedy
    Mar 5, 2006
  4. DeltaOne
    Replies:
    31
    Views:
    892
    S.Tobias
    May 20, 2005
  5. kiran
    Replies:
    12
    Views:
    1,154
    Scott Sauyet
    Dec 7, 2011
Loading...

Share This Page