#include <cstdlib>
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)
{
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];
fseek(in,-1,SEEK_CUR);
fputc(c,in);
fseek(in,ftell(in),SEEK_SET);
i++;
if(i==len)i=0;
}
fclose(in);
printf("\nNow open the TEXT.\n",infile);
}