Formatted output using ofstream in C++

[eranga262154]

I'll explain my issue in this way.

I've use a structure to get some data of a byte stream as follows.

1. struct pac_cont
   2. {
   3.     unsigned int des_list ;
   4.     unsigned int mem_ID ;
   5.     unsigned char dm_con ;
   6.     unsigned char ser_ID ;
   7.     unsigned short act ;
   8.  };

Now I want to write some values finding by using above variables, to a text file, of a function. Try it as follows.

1. void dataExtract(int length, char *buffer)
   2. {
   3.      struct pac_cont* p = (struct pac_cont*)buffer;
   4.        
   5.      printf("dest %d member %d data %d ser %d act %d\n",p->des_list,p->mem_ID,p->dm_con,p->ser_ID,p->act) ;
   6.        
   7.      ofstream filedata ;
   8.      filedata.open( "RecordData.txt", ios::app ) ;
   9.        
  10.     if(filedata.is_open())
  11.     {
  12.              filedata << p->des_list << "\t" << p->mem_ID << "\t" << p->dm_con << "\t"<< p->ser_ID << "\t" << p->act << "\n";
  13.               
  14.              filedata.close() ;
  15.      }
  16.     else
  17.    {
  18.              filedata << "Wrong\n" ;
  19.     }
  20. } 

That printf gives the exact values I need on the command prompt. But the line filedata give some annoying output to the text file. I know that how format the output in printf, but no idea how to use in filedata

Someone can give a clue to me.
Thanks

[Salem]

%d will treat a variety of similar types as all being int, including chars.

When you << a char, that is exactly what you'll get, a char. If that happens to be a non-printable char, then your output file will appear funny.

Try casting your chars to ints before outputting them

[eranga262154]

You mean simple explicit conversion, like (int) on struct pointer?

[Salem]

Try it.

[eranga262154]

I've try it and still checking the result with actual one.

By the time I've try to format the output in setbase() of <iomanip> for base 10(because typically it is integer value we use). But it not works. What can be issue there.

[Salem]

So you did this?

filedata << p->des_list << "\t" << p->mem_ID << "\t" 
         << (int)p->dm_con << "\t"<< (int)p->ser_ID << "\t" << p->act << "\n";

[eranga262154]

Yes, that is what I've try.

[Salem]

Dunno then, it works here

#include <iostream>

int main() {
    char c = 'A';
    std::cout << c << std::endl;
    std::cout << (int)c << std::endl;
    return 0;
}

$ g++ -W -Wall -ansi -pedantic  foo.cpp
$ ./a.exe
A
65

[Salem]

Bear in mind that you're appending to the file, so any new results as a result of the code change will be at the END of the file.
Don't keep staring at the start of the file :)

[eranga262154]

Dunno then, it works here

#include <iostream>

int main() {
    char c = 'A';
    std::cout << c << std::endl;
    std::cout << (int)c << std::endl;
    return 0;
}

$ g++ -W -Wall -ansi -pedantic  foo.cpp
$ ./a.exe
A
65

Thanks, actually why I'm confusing with this topic is that struct are really new for me.