interesting problem in turbo C++, involving fopen

From: git_cs (git_cs_at_rediffmail.com)
Date: 04/30/04 

Date: 29 Apr 2004 23:28:41 -0700

Hey, guys and gals
        Somedays ago, I had asked for the DES algorithm in C language.
Although I have written the algorthim in C myself, I am facing a
peculiar problem, which I hope some of u guys and gals solve.
        I use Turbo C++ version 3.0 and WINXP as the operating system.
        Pls observe the following program.

1 #include<stdio.h>
2 #include<conio.h>

3 main()
4 {
5 int i,j;
6 int ak;
7 char ch;
8 FILE *fp,*fs;
9 clrscr();
10 i=0;
11 fs=fopen("ak4.txt","w");
12 for(i=0;i<256;i++)
13 {
14 fputc(i,fs);
15 }
16 fclose(fs);
17 i=1;
18 fs=fopen("ak4.txt","r");
19 fp=fopen("ak5.txt","w");
20 i=0;
21 while(i!=EOF)
22 {
23 i=fgetc(fs);
24 printf("%d\n",i);
25 fprintf(fp,"%c",i);
26 fprintf(fp,"%d ",i);
24 }
25 }
                

I run the above program in Turbo C++, and winxp as operating system.

Then the file "ak4.txt", is created which will contain all the ascii
characters from 0-255.
But, from line 18, when I open the file "ak4.txt", and try to copy its
contents to another file
"ak5.txt", you will find a very interesting output.

 First, that character whose ascii value is "13", has been ignored.
You can verify it on the screen output by pressing "Alt+F5", or in the
new file "ak5.txt".

Second, at character with ascii value "26", the while loop at line 21,
exits . In the file "ak5.txt", only 0-25 ascii characters(except 13)
are copied.

So, if insert the following line

                if(i==26)
                        continue;

before line 14, then all the characters other than 26,13 will be
copied in file "ak5.txt".

Whew!!!, I hope I have been able to explain u.

My question: I am doing a project on DES algorithm. When I encrypt a
file, any ascii value from 0-255, might be the output. So, when I
want to decrypt it, those ascii values 13,26 do appear sometimes, and
cause the decryption to go haywire(13) or to exit the program
itself(26).

So, my friends is there a way out of this mess?

Have any of you faced the same problem. If yes? how did you solve it?

Will changing the compiler solve the problem?

Is there gcc compiler for windows too?

Please suggest some ideas. Because I intend to make a project which
runs on windows.

Note: The same DES program runs just fine on Linux.

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