điểm phần tăng dần 3/3

#include <stdio.h>
#include <string.h>
#define N 100

typedef struct
{
	float diem1 , diem2 , diem3 ;

}diemsinhvien ;

typedef struct
{
	int masv ;
	char tensv [N] ;
	diemsinhvien diem ;

}sinhvien ;

FILE *f ;
sinhvien sv ;
int const size=sizeof(sinhvien);
void themmoi ( )
{
	int them ;
	scanf ( "%d\n" , &them ) ;
	int sosv = 1 ;                         //  0 thì dúng hon co mà thích d? 1 //
	f = fopen ( "B17DCAT089.bin", "rb" );
		while ( fread ( &sv , size , 1 , f ) == 1 )
			sosv++;
	fclose (f) ;
	int i;
	f = fopen ( "B17DCAT089.bin" , "ab" ) ;
	for ( i = sosv ; i < sosv + them  ; i++ )
	{
		sv.masv = i ;
		gets ( sv.tensv ) ;
		scanf ("%f%f%f\n" , &sv.diem.diem1 , &sv.diem.diem2 , &sv.diem.diem3 ) ;
		fwrite ( &sv , size , 1 ,f) ;
	}
	fclose (f) ;
	printf ( "%d\n" , them ) ;
}

void capnhat (  )
{
    sinhvien svsua ;
	scanf ( "%d\n" , &svsua.masv ) ;
	gets ( svsua.tensv ) ;
	scanf ( "%f %f %f" , &svsua.diem.diem1 , &svsua.diem.diem2 , &svsua.diem.diem3 ) ;
	f = fopen ( "B17DCAT089.bin" , "rb+") ;
	rewind (f) ;
	while ( fread ( &sv , size , 1 , f ) == 1)
	{
		if ( sv.masv == svsua.masv )
		{
			fseek ( f , - size , SEEK_CUR );
			fwrite ( &svsua , size , 1 , f ) ;
			break ;
		}
	}
	fclose (f) ;
	printf ( "%d" , svsua.masv ) ;
}

void dssv ()
{
	f = fopen ( "B17DCAT089.bin"  , "rb" ) ;
	rewind ( f ) ;
	while ( fread ( &sv , size , 1 ,f ) == 1)
	{

		if ( sv.diem.diem1 < sv.diem.diem2 && sv.diem.diem2 < sv.diem.diem3 )
		{
			printf ( "%d %s " , sv.masv , sv.tensv )  ;
			printf ( "%.1f %.1f %.1f \n"  , sv.diem.diem1 , sv.diem.diem2 , sv.diem.diem3 ) ;
		}

	}
	fclose ( f ) ;

}
int main ()
{
	int chucnang ;
	scanf ( "%d" , &chucnang ) ;
	switch ( chucnang )
	{
		case 1 : themmoi () ;
		break ;
		case 2 : capnhat () ;
		break ;
		case 3 : dssv ();
		default : break;
	}
}