How can i delete the last 48 bytes in a file ?

Question

I have a file where i would like to delete the only last 48 bytes. I have not heard of any function or class where i can implement such a thing. Please help me out here !

Answer 1

here's my C Code:
But my remove and rename methods are not working !!
void deleteStudentRecord()
     int enrollNo;
     int counter=0;
     FILE *ptr2 = fopen("c:\\file2.txt","a");
     int records = getNoOfRecords();
     refresh();
     fflush(stdin);
     printf("Enter Enrollment Number:\n");
     scanf("%d",&enrollNo);
     while(counter!=records)
          fread(&var,sizeof(struct student),1,ptr);
          if(var.enrollNo==enrollNo)
          else
               fwrite(&var,sizeof(struct student),1,ptr2);
          counter++;
     fcloseall();
     remove("c:\\file.txt");
     rename("c:\\file2.txt","c:\\file.txt");
     printf("Press any key..");
     getch();
}