Hello,

         Do anyone know how to create a binary file ".dat"?  I know how to use the C Programming to do it, but for C++ I have no ideal.  Do anyone have the C++ program source code which able to add, delete, list and modify in the binary file ".dat"?

Thank you

Joan Choong

• What you want? Infos about :

1. Working with files (binary or text) in C++ ?
2. Specific operations in '.dat' files (in C++) ?

• Do you want detailed infos or just some points ? (have any references like books, MSDN ?)

Hello Mohammad Rastkar,

                     Actually I want a binary file (as database) but not text file in C++ which can add, delete, list and modify.  ".dat" file is one of the database file in C++.  I need the detailed infos.  Some of the C++ books I had go through but can't find it.

Please help if you know about it.

Thanks,

Joan Choong

OK!

Hello joan...

-> I hope the following infos will help you...

-> Below I've separated the infos in three parts :

• < Points >    : Just the HowTo.
• < Detailed > : More infos about functions (from MSDN)
• < Example > : A complete example (my code) (.cpp file). Want the file ? Click here for download :  Employee_Record.cpp . Also see my code sample : [C++] Simple Multiplication Test - Involves with : files & strings & arrays & ...

-> If you want more infos -> Just tell me

< Points >

• include the 'fstream' file : #include <fstream> (You should include this file for all file interactions).
• Open the file with 'open' method, that has 'ios::binary' for second parameter. (the file extension has NO effect on file contents [you can use files without extension], the 'open' method specifies the interaction mode (binary,text,..))
• Use one of these ways, for I/O from file :
  1. Just like the standard 'iostream' (cin & cout), you can use '>>' and '<<' with language types (int, cahr, ..) and overload these operators to use with your own types.
  2. You can also use Structures (struct), and input them into file with 'write' method, and have an output with 'read' method.                                                                                                                            3.You can interact with a binary file as text (and vice versa) and Using 'get', 'put',... methods that is used with text files ('getline' will work unexpected in binary parts of file).
• when your interaction with file ends, close the file with 'close' method.

Hello Mohammad Rastkar,

                                          Thanks a lot for your infors.  I want the .CPP file (add, delete, modify and list) due with Class instead of Structured.  Do you have?  Please e-mail to this e-mail address joancross2004@yahoo.com

Thanks.

Joan Choong

Hello Mohammad Rastkar,

I've been looking for ways to delete files by extension in a certain directory using C/C++, (e.g. *.txt) I made a program that creates a specific data file every time you use it. But I need to remove these files after I have collected the data.

My first solution was to store the specific filenames into a single file then when I need to remove all the files, I have to recall the filenames string then one by one remove by commande remove(). But I dont think its practical.

 Please advise if you have better solutions, thanks! Appreciate it.

Rgrds,

Hazof

Hello Hazof,

•  If you want, for example, delete all '.txt' files from 'c:\', you can use the following command :

#include <cstdlib> // for system(), maybe including '<iostream>' with 'using namespace std;' be sufficient

system( "del c:\\*.txt" ); // 'system()' will execute a command, (those you can run in 'CMD.exe')

=> With 'del' dos command, you have many options that's not in 'remove()', like : delete readonly files (by : 'del /F' )

• Since you can execute any 'DOS command' with 'system()', then you can do many things! Here, you can make a directory, and create all of your files there, then delete that directory. The direct commands are :

#include <direct.h> // for mkdir(), rmdir()

mkdir( "c:\\my_tmp" ); // creates directory : when succeeds, return 0; for error, return -1

rmdir( "c:\\my_tmp" ); // deletes a directory, return values are same as 'mkdir'

=> 'rmdir()' can only delete empty folders, but with the following command you are not limited! :

system( "rd /Q /S c:\\my_tmp" ); // deletes 'my_tmp' folder, and all files and folders in it

=> Also, to delete all the files in a directory :

system( "del /Q c:\\my_tmp" ); // using '/Q' switch to not confirming deletion of all files

Hello Mohammad Rastkar,

                                         Thanks a lot for ur post. I want the .CPP file (add, delete, modify and list) due with Class instead of Structured.  Do you have?  Please e-mail to this e-mail address chandrajithm@yahoo.com

Thanks.

CJ

Hello  chandrajith.m,

I sent an email to you with the file attached.

Hi Mohammad and guys

You have shown a good program for demonstration.  I have compiled and run the program on my Windows XP computer.  I have noticed that, when the program takes an integer 26 as an input for AGE or ID, something funny happens.  Tr it!!  It may happen because my computer has got Winodws XP and VC++ 6.0.  I am not sure!!  If somebody can comment on it, I will be gratefull.  By the way, I fixed the problem by opening the data file in the binary mode(i.e  fs.open( "Employees", ios::in|ios::binary )).

 All the best

Chong

Hi chong & All,

=> Thanks chong ! your clue does the work! 'binary' mode just solves that. I've changed and corrected the sample program (see in 4th post in this thread to download or view that).

 =>  I think the answer of 'why 26 is problematic?' is :

When you're writing a structure in a file, despite of file mode(binary or text), it will be written in binary format, then when you want to read from that file later, if you read in binary mode, there is no problem, but if you want to read in text mode, and if previously you wrote '26' as an integer member of a structure in the file, now when you want to read structure from the file, when 'read()' wants to read integer member, it doesn't read '26' as an integer, it reads '^Z' (Ctrl+Z) since it's in binary format, and '^Z' means end of input, then it stops reading. Then actually you have nothing from file! Why '26' means '^Z'? see MSDN 'ASCII Character Codes' section(or see ASCII codes from any other resources), then you'll see(in 'Chart 1') that '26' is the ASCII code of '^Z'.

Then never read a binary file in text mode, unless you really intend that!

I am working on a binary file that will store various bits of information about customers (name, address, city, state, zip, balance, date of last payment, etc).  I can create and write to the file no problem, but I am not sure how to delete a specific record or search for a record and the modify it.  I am using a structure to store the data for each customer, which is working just fine.  Any help will be much appreciated.

--Paul T 

Hi paul trip,

=> Modify : you should first find the reacord position (by searching the file), then use 'seekp' function to change the file_pointer at the first of the record (if 'seekp()' doesn't work, just closing the file and reopening that may not put the file_pointer at the first of the file (even using 'clear' function), then you should use two 'fstream's or a pointer (fstream*) and delete that, then create a new one, then use 'seekp()'). When the file_pointer was at the first of the record, then write the new info(struct) to the file (it will replace old info with new one).

=> Delete : There is no method to delete from a file, then you should do that by writing whole of file in a new file, without deleted record(s) (you can first specify deleted ones (when deleting) with a change in the record (e.g. set the ID to 0 (if no one has ID of 0)), then later, really delete records by creating a new file).

=> Also : There is an approach using class 'string', that is used as an example in this code sample :

[C++] Simple Multiplication Test - Involves with : files & strings & arrays & ...

It has this advantages : speed (just two file interactions), flexibility (using all of 'class string' methods), simplicity (less codes), ...

but just you can't use structs explicitly (you should use each field separately).

Hello Mohammad Rastkar,

Thanks a lot for ur post. I want the .CPP file (add, delete, modify and list) due with Class instead of Structured. Do you have? Please e-mail to this e-mail address onglim1987@hotmail.com

I try to download from -> Filed under: delete modify update record file  but the page not found.

Thanks.

OL