ios::binary.... a discussion (mostly)

This is a discussion on ios::binary.... a discussion (mostly) within the C++ Programming forums, part of the General Programming Boards category; Code: #include <fstream> using namespace std; int main() { ofstream outs; outs.open("file.dat", ios::binary); outs << "ABCD" << "\n\n\n"; outs.write("1234",4); outs.close(); ...

  1. #1
    _B-L-U-E_ Betazep's Avatar
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    ios::binary.... a discussion (mostly)

    Code:
    #include <fstream>
    using namespace std;
    
    int main()
    {
    
         ofstream outs;
    
         outs.open("file.dat", ios::binary);
    
         outs << "ABCD" << "\n\n\n";
    
         outs.write("1234",4);
    
         outs.close();
    
    return 0;
    }
    ok... so we have a handly little binary file named file.dat that when opened with notepad contains...

    ABCD###1234

    (count the #s as small black squares)

    What is the purpose of this? I skipped the whole binary process in file I/O because it didn't interest me at the time... now it does.

    Over the past couple of years, we have had a lot of questions regarding binary files. For some reason, all this time, I was led to believe that binary files were not human readable. (Couldn't have been more off the mark with that thought...)

    What the heck do you use a binary file for that a ascii file cannot do?

    As naive as it may sound... I actually thought when I opened the file I would see a bunch of ones and zeros... you know... binary.... LOL.

    Blue

  2. #2
    Something Clever ginoitalo's Avatar
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    Well Betazep,

    Binary files have a much much much faster access/retrieval time.

    Binary files are also much nicer when storing encapsulated data as in classes/struct's.

    You can move n bytes forward/backward
    or n bytes from the beginning or the end.

    It's a little more cryptic to the untrained eye.

    ...as to the storing or 1's and 0's
    I'm not sure but I'd like to know too

  3. #3
    _B-L-U-E_ Betazep's Avatar
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    OIC... I am going to try that.
    Blue

  4. #4
    Registered User xds4lx's Avatar
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    Here go here and look at this its all about file I/O in C++: http://www.cpp-home.com/FileIO_tutorial.php just scroll down in it, it has a pretty good section on binary files.
    "only two things are infinite, the universe and human stupidity, and im not sure about the former." - albert einstein

  5. #5
    _B-L-U-E_ Betazep's Avatar
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    Excellent link... thanks.
    Blue

  6. #6
    Something Clever ginoitalo's Avatar
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    Here's something I cooked up :

    Code:
    #include<iostream.h>
    #include<fstream.h>
    #include<string.h>
    
    
    struct applicant {
    	char name[61];  // applicant's name
    	char phone[21]; // phone number
    	long date;      // date of application in yyyymmdd format
    };
    
    
    int main(void){
    
    	fstream fs("2111112.aaa", ios::in | ios::out | ios::binary);
    
            applicant x;
                    x.date=9;
                    strcpy(x.name,  "ginoitalo");
                    strcpy(x.phone, "13281");
    
    
    cout<<endl<<"--------------"<<endl<<"Name="<<x.name<<endl;
    cout<<"Date="<<x.date<<endl;
    cout<<"Phone="<<x.phone<<endl<<"--------------"<<endl<<endl;
    
            fs.seekp(0, ios::beg);
            fs.write( (char*)&x, sizeof(applicant) );
    
            fs.seekg(0, ios::end);
    
    
    cout<<"End of file        = "<<fs.tellg()        <<endl;
    cout<<"Size of applicant  = "<<sizeof(applicant) <<endl;
    
            int recs = ( 1*fs.tellg() / sizeof(applicant) );
            cout<<endl<<"Records in file="<<recs<<endl;
    
    
            applicant in;
            fs.seekg(0, ios::beg);
            fs.read((char*)&in, sizeof(applicant) );
    
    
    cout<<endl<<"--------------"<<endl<<"Name="<<in.name<<endl;
    cout<<"Date="<<in.date<<endl<<"Phone="<<in.phone<<endl;
    cout<<"--------------"<<endl<<endl;
    
    return 0;
    }

  7. #7
    Registered User xds4lx's Avatar
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    Hmm, you didnt even try to run that code did you b/c I can tell you its not going to work haha.
    "only two things are infinite, the universe and human stupidity, and im not sure about the former." - albert einstein

  8. #8
    Something Clever ginoitalo's Avatar
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    Runs fine in VC++ 6.0

  9. #9
    Something Clever ginoitalo's Avatar
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    and amazingly BCC32

    ..well looks like no errors..

    perhaps xds4lx will do his homework before posting next time

  10. #10
    Registered User xds4lx's Avatar
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    Doesnt here, and i have Visual C++ 6 Professional w/ service pack 5 + the processor pack. It doesnt work! You never test to see if the file opened, a big no no! Then when you try to load it in from file its loading garbage, and dont tell me how to program ive been doing it a lot longer than you im sure! Plus you have typos in there so hmm that cant be runnable!. And you are using old C++ headers that are non-standard, try using the standard headers w/ out the .h
    Last edited by xds4lx; 04-11-2002 at 09:35 PM.
    "only two things are infinite, the universe and human stupidity, and im not sure about the former." - albert einstein

  11. #11
    Something Clever ginoitalo's Avatar
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    #include<iostream>
    #include<fstream>
    #include<string>

    using namespace std;


    Works fine.

    and...What typos ?

  12. #12
    Something Clever ginoitalo's Avatar
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    p.s.

    Using Visual C++ Enterprise edition

    and

    Borland 5.5 Command line

  13. #13
    _B-L-U-E_ Betazep's Avatar
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    Fight!!! j/k

    I get the idea though. I will try it out when I have the time.
    Blue

  14. #14
    Registered User xds4lx's Avatar
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    Here, heres a screenshot of the results of execution.
    --------------
    Name=ginoitalo
    Date=9
    Phone=13281
    --------------

    End of file = -1
    Size of applicant = 88

    Records in file=48806446

    --------------
    Name=
    ._ginoitalo
    Date=-858993460
    Phone=._ginoitalo
    --------------

    Press any key to continue
    "only two things are infinite, the universe and human stupidity, and im not sure about the former." - albert einstein

  15. #15
    Something Clever ginoitalo's Avatar
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    .sigh.

    The things I do....

    This will show the file doesn't read trash and that the file is properly opened and that it truly reads from the file
    (which it all did in the above version but wasn't evident enough to some)

    ...and there will be no fighting on the board
    or I will call your mother :)

    Code:
    #include<iostream>
    #include<fstream>
    #include<string>
    
    using namespace std;
    
    
    struct applicant {
    	char name[61];  // applicant's name
    	char phone[21]; // phone number
    	long date;      // date of application in yyyymmdd format
    };
    
    
    int main(void){
    
    	fstream fs("2111112.aaa", ios::in | ios::out | ios::binary);
    
    	applicant x;
                x.date=9;
                strcpy(x.name,  "ginoitalo");
                strcpy(x.phone, "13281");
    
    	cout<<endl<<"--------------"<<endl<<"Name="<<x.name<<endl;
    	cout<<"Date="<<x.date<<endl;
    	cout<<"Phone="<<x.phone<<endl<<"--------------"<<endl<<endl;
    
    	if(!fs.fail()){
    			fs.seekp(0, ios::beg);
    			fs.write( (char*)&x, sizeof(applicant) );
    			fs.close();
    	}
        else{
    		exit(99);
    	}    
    
    
    	// File is Totally Closed as of now.
    
    	// Re-open to prove it doen't read grabage.
    	fstream fs2("2111112.aaa", ios::in | ios::out | ios::binary);
    	
    	if(!fs2.fail()){
    
    		fs2.seekg(0, ios::end);
    		
    		cout<<"End of file        = "<<fs2.tellg()        <<endl;
    		cout<<"Size of applicant  = "<<sizeof(applicant) <<endl;
    
            int recs = ( 1*fs2.tellg() / sizeof(applicant) );
            cout<<endl<<"Records in file="<<recs<<endl;
    
            applicant in;
            fs2.seekg(0, ios::beg);
            fs2.read((char*)&in, sizeof(applicant) );
    		fs2.close();
    
    		cout<<endl<<"--------------"<<endl<<"Name="<<in.name<<endl;
    		cout<<"Date="<<in.date<<endl<<"Phone="<<in.phone<<endl;
    		cout<<"--------------"<<endl<<endl;
    	}
    	else{
    		exit(98);
    	}
    
    
    return 0;
    }

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