Hàm sao chép dữ liệu từ file text
void COPY_FILE()
{ FILE *f1=fopen("F1.doc","r");
FILE *f2=fopen("F2.doc","w");
char ch;
while(!feof(f1))
{
ch=fgetc(f1);
if(ch!=EOF) fputc(ch,f2);
}
fclose(f1);fclose(f2);
cout<<"\n COPY DONE";
}