/*************************************************************************
*          Encoding an ASCII text using a random encoding table          *
* ---------------------------------------------------------------------- *
* The text to encode is in file codage.dat.                              *
* The random encoding table is in file code.lst.                         *
* The output encoded text is in file codage.lst.                         *
*                                                                        *
* The text can be decoded by  decodage.exe that must have access to      *
* code.lst and codage.lst files.                                         *
* ---------------------------------------------------------------------- *
* SAMPLE RUN:                                                            *
* File codage.dat contains:                                              *
*                                                                        *
* Program ASCII;                                                         *
* Uses WincrtMy;                                                         *
*                                                                        *
* VAR                                                                    *
*     i: word;                                                           *
*                                                                        *
* BEGIN                                                                  *
*   for i:=160 to 255 do                                                 *
*     write(i:4,' ',chr(i));                                             *
*   Readkey;                                                             *
*   DoneWinCrt                                                           *
* END.                                                                   *
*                                                                        *
* The output file code.lst contains:                                     *
*                                                                        *
* !h"k#c$2%#&^'v(1):*$+",e-H.L/50}102o3|4j5t6D7R8?9J:G;.<K==>Z?O@3AUBiCg *
* DbEmFSG(HWIxJfK)L+MNN&OAPBQ]R7S;T>UlVYWVXTY,Zw[!\C]-^n_/`Fayb8c{d9edfz *
* g~hQi\jqk[l'm@n4oPprqsr*s<tau%v_wIxEyuzX{`|6}M~p                       *
*                                                                        *
* (! is coded h, " is coded k, # is coded c, etc.)                       *
*                                                                        *
* The output file codage.lst contains;                                   *
*                                                                        *
* B*P~*y@ U;gxx.                                                         *
* l<d< V\4{*aNu.                                                         *
*                                                                        *
* YU7                                                                    *
*     \G IP*9.                                                           *
*                                                                        *
* im(x&                                                                  *
*   zP* \G=0D} aP ott 9P                                                 *
*     I*\ad1\Gjev ve{Q*1\::.                                             *
*   7dy9[du.                                                             *
*   bP4dV\4g*a                                                           *
* m&bL                                                                   *
*                                                                        *
*                                    C++ Release By J-P Moreau, Paris.   *
*                                           (www.jpmoreau.fr)            *
*************************************************************************/
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <ctype.h>
#include <math.h>   
#include <time.h>

#define MINCAR 33    // ASCII characters from 33 to 126 only 
#define MAXCAR 126
#define MAXSTR 81    // lines of length 80 

char  A[MAXCAR+1],Z[MAXCAR+1];
int   alea,fait,i,j;  
char  ligne[MAXSTR];
char  codee[MAXSTR];


void main(void)  {
  FILE *fp1,*fp2, *fp3;
  srand((unsigned)time(NULL)); //initialize random generator

  if((fp1=fopen("codage.dat","r"))==NULL) {
       printf("\n Impossible to open input text file: codage.dat");
       exit(1);
  }
  if((fp2=fopen("codage.lst","w"))==NULL) {
       printf("\n Impossible to open output encoded file: codage.lst");
       exit(1);
  }   
  if((fp3=fopen("code.lst","w"))==NULL) {
       printf("\n Impossible to open the random table file: code.lst");
       exit(1);
  }     
  for (i=MINCAR; i<MAXCAR+1; i++) A[i]=i;  
  
  // generate a random encoding table        
  do {
    alea=rand(); 
  } while (alea > MAXCAR-MINCAR);                   
  Z[MINCAR]=MINCAR+alea;  
  for (i=MINCAR+1; i<MAXCAR+1; i++) 
    do { 
      do {
        alea=rand(); 
      } while (alea > MAXCAR-MINCAR);        
      Z[i]=MINCAR+alea;
      fait=1;
      for (j=MINCAR; j<i; j++) if (Z[j]==Z[i]) fait=0;
    } while (fait==0);      
                                            
  // encode input text line by line and save                                            
  while (!(feof(fp1))) {
    fgets(ligne,MAXSTR,fp1);
    strcpy(codee,ligne);
    for (i=0; i<MAXSTR; i++)
      for (j=MINCAR; j<MAXCAR+1; j++)
	if (ligne[i]==A[j]) codee[i]=Z[j];
    fprintf(fp2,"%s",codee);
  }
  fclose(fp1);                     
  fprintf(fp2,"\n");
  fclose(fp2);

  // Print random encoding table in file code.lst 
  for (i=MINCAR; i<MAXCAR+1; i++) {
    fprintf(fp3,"%c%c",A[i],Z[i]);
    if (((i-MINCAR+1) % 35)==0) fprintf(fp3,"\n");
  }  
  fprintf(fp3,"\n");  
  fclose(fp3);
  printf("\n Program terminated. Results in file codage.lst\n\n");
}

//end of file codage.cpp