Thread: How to write file .txt which can read-only.

I use Visual C++ 6.0. My source is below. I want to write text file which can read-only. If you know how to edit source to do that ,please tell me. Thank you very much.

#include <stdio.h>
int main()
{
FILE *outp;
char *output_filename;

output_filename = "output.txt";
outp = fopen(output_filename, "w");

fprintf(outp, "1");

fprintf(outp, "\n");

if (output_filename)
{
fclose(outp);
}
}

PS. I really want to create logfile but I do not know how to do.So I create text file instead. Does text file (read-only) and logfile have much difference?

Just a tip, use the [ code ] tag.

Code:

#include <stdio.h> 
int main() { 
   FILE *outp; 
   char *output_filename; 

   output_filename = "output.txt"; 
   outp = fopen(output_filename, "w"); 
 
   fprintf(outp, "1"); 

   fprintf(outp, "\n"); 

   if (output_filename) { 
      fclose(outp); 
   } 
}

you cant make a file trully readonly... so your prob better off encrypting it...

How do you encrypt it?

with alogithorims Did I spell that right?

If it is just a log file and isn't overly important then XOR encrytion will do quite nicely. It really shouldn't be used for very secure info but as it sounds it would work good for you cause u want sumthing simple.

XOR Encryption works like this

A B A XOR B
T T F
T F T
F T T
F F F

so your code should look sumthing like this

Code:

#include <iostream.h>

int main()
{
  char string[6]="Hello";//your text you want encrypted
  char key[6]="ABCDE";//you always need a key
  for(int x=0; x<10; x++)
  {
    string[x]=string[x]^key[x];//this loop does the actual encrytion
    cout<<string[x];                //whick i explained below
  } 
  return 0;//end your program
}

The symbol for XOR is ^ the actual algoithm for XORing text is
'c=a^b' c=decryted file a=file you want encrypted and b= your key. To decrypt you just do this 'a=b^c'.

If you are a little lost there is a good tutorial located here http://www.cprogramming.com/tutorial/xor.html

Some people like to play with the XOR encryption technique to make it more secure. But if the text in your log isn't the most important thing in the world then simple XORing should be fine for you

you can set the read-only flag. in dos the command is "attrib +r filename.ext". you can try a system call like that.