#include
#include
main()
{
char password[10],len,i=0,ch,c;
char infile[20];
FILE * in;
printf( "FILE NAME:");
scanf("%s",infile);
if((in=fopen(infile,"r+"))==NULL)< /p>
{
printf("ERROR!");
exit(0);
}
printf ("KEY:");
scanf("%s",password);
len=0;
while(password[len]!= 0)len++;
while((ch=fgetc(in))!=EOF)
{
c=ch^password[i];< /p>
fseek(in,-1,SEEK_CUR);
fputc(c,in);
fseek(in,ftell(in),SEEK_SET);< /p>
i++;
if(i==len)i=0;
}
fclose(in);
printf("\nNow open the TEXT.\n",infile);
}
Thanks