lanjutan manipulasi file pada c++

MEMBACA FILE
#include
#include
#include
#include
#include
#include
#include

class Kelas
{
private:
int data;
public:
int info_kelas();
};
void baca_kelas(Kelas pti);
void main()
{
Kelas kelas_pti;
baca_kelas(kelas_pti);
}
int Kelas::info_kelas()
{
cout <<"Data : "<> ganti;
if(ganti=='Y'||ganti=='y') {
int result;
char oldname[] ="c.txt";
char newname[20];
printf("Nama Baru: ");
gets(newname);
result= rename( oldname , newname );
if ( result == 0 )
puts ( "File successfully renamed" );
else
perror( "Error renaming file" );

}

}