C++ Program to read from IFS

[vikramx]

While I do realize we can call the C functions from a RPG program to read the IFS files, I am trying to write a pure C/C++ code to read a file from the IFS and having a bit of a problem

Following is my code

#include<fstream.h>
void main()
{
   fstream f1,f2;
   char input;
   f1.open("\dev\myfolder\test.txt",ios::in);
   f1>>input;
   cout<<input;
   f1.close();

   f2.open("\dev\myfolder\test1.txt",ios:out);
   f2<<"this is test text";
   f2.close();
}

Now my issue here is when reading the file opened using f1, I am not getting the required characters. However if I open test1.txt using wrklnk or notepad, I see the text correctly.

Edit1: One possible way I found is that my C++ program is able to read files with CCSID of 37 only. The others are giving me garbage characters as its not able to recognize it.

Any other way around this?

[vazymimil]

Re: C++ Program to read from IFS

Hello,

I'm not a C++ programmer but I gave it a try a few years ago, and from what I see in my example you have to use ios::text like that

f1.open("\dev\myfolder\test.txt",ios::in||ios::text);

[vikramx]

Re: C++ Program to read from IFS

Thanks a lot for the info. I finally got it to work by actually accessing the C functions with a RPG program since it seemed like my pure C code will not suffice for what I wanted to do.

[jamief]

Re: C++ Program to read from IFS

Can you post a snippet of what you ended up with?

jamie

[MichaelCatalani]

Re: C++ Program to read from IFS

While I do realize we can call the C functions from a RPG program to read the IFS files, I am trying to write a pure C/C++ code to read a file from the IFS and having a bit of a problem

Following is my code

#include<fstream.h>
void main()
{
   fstream f1,f2;
   char input;
   f1.open("\dev\myfolder\test.txt",ios::in);
   f1>>input;
   cout<<input;
   f1.close();

   f2.open("\dev\myfolder\test1.txt",ios:out);
   f2<<"this is test text";
   f2.close();
}

Now my issue here is when reading the file opened using f1, I am not getting the required characters. However if I open test1.txt using wrklnk or notepad, I see the text correctly.

Edit1: One possible way I found is that my C++ program is able to read files with CCSID of 37 only. The others are giving me garbage characters as its not able to recognize it.

Any other way around this?

If I understand what you are trying to do, then you are missing one step in your C program. You have to perform an ascii to ebcdic conversion on a file that is in ascii format. The reason for this is that, even though you are using C to do this, the platform in which your C program is running is EBCDIC. So, by default, it believes its going to be reading in EBDIC. If the file is in ascii format, you will have to read it, then translate the contents from ascii to ebcdic.

The reason a CCSID 37 file works is because that is ebcdic, and no translation is needed.

[MichaelCatalani]

Re: C++ Program to read from IFS

As kind of a backwards example, look at this code:

                                                                              
/* COMPILE OPTIONS  -  CRTBNDC SYSIFCOPT(*IFSIO)                          */  
                                                                              
#include <stdio.h>                                                            
int main(void)                                                                
{                                                                             
    FILE *fd1;                                                                
    char SomeData[256];                                                       
    int x;                                                                    
    fd1 = fopen( "/ifstest/newfile.txt" , "w" );                              
    fprintf( fd1 , "Some Test Data \n" );                                     
    fclose(fd1);                                                              
    fd1 = fopen( "/ifstest/newfile.txt" , "r" );                              
    fgets( SomeData, 256, fd1 );                                              
                                                                              
    printf( "Data From File: %s\n" , SomeData );                              
       printf( "\n" );                                                        
       fclose( fd1 );                                                         
   }

This will write data to a file on the IFS. (You would have to create a folder on the IFS named "IFSTEST" for it to work. And Make sure to see the compile options at the top of the program.) Data will be written to the file in EBCDIC. If you use notepad on this file, it will show garbage. If you copy this garbage data into an online translator (ie http://www.pacsys.com/ebccnv.htm) it will show you the correct data.

[vikramx]

Re: C++ Program to read from IFS

Thanks Michael. I thought it was a translation problem but felt that if the C APIs within the RPG could read it, the normal C program could also be able to.

@Jamie
I basically used your method to access IFS files using the C API functions (read, open, close). Using a similar logic to your readifs2 program you posted on the thread on multi-format csvs (Hope you didnt mind me taking a little hint from you).

0003.00,D OpenFile        PR            10i 0 Extproc('open')
0004.00,D                                 *   Value
0005.00,D                               10i 0 Value
0006.00,D                               10u 0 Value Options(*NOPASS)
0007.00,D                               10u 0 Value Options(*NOPASS)
0008.00,
0009.00,D ReadFile        PR            10i 0 Extproc('read')
0010.00,D                               10i 0 Value
0011.00,D                                 *   Value
0012.00,D                               10u 0 Value
0013.00,
0014.00,D CloseFile       PR            10i 0 Extproc('close')
0015.00,D                               10i 0

Rest of it is similar to your readifs2 program except that it handles all kinds of delimiters (provided its given correctly by the user).

Basically what I was trying to do is read a file from IFS (Could be csv, text tab delimited or any kind of delimited file) and convert this into a PF by automatically generating the DDS based on the contents within the IFS file. This program reads the IFS file (based on parameters passed), generates the ideal DDS (each field length if based on the maximum length of data within the specific column), creates the physical file and copies the data into the physical file using the CPYFRMIMPF command.

Of course the limitation here is that the DDS will only have character fields since I still see no way of determining what type of field it should be.