Ghi file kieu nhi phan

#include<conio.h>
#include<stdio.h>
#include<string.h>
#define max 100

typedef struct TaiKhoan
{
    char MaTK[10];
    char TenTK[30];
    long SoTien;
}TK;

void Nhap1TK(TK &x)
{
    printf("\n Nhap Ma TK:");
    fflush(stdin);
    gets(x.MaTK);
    printf("\n Nhap Ten TK:");fflush(stdin);
    gets(x.TenTK);
    printf("\n Nhap So Tien:");
    scanf("%ld",&x.SoTien);
}
void Xuat1TK(TK x)
{
    printf("\n Ma TK:%s",x.MaTK);
    printf("\n Ten TK:%s",x.TenTK);
    printf("\n So Tien:%ld",x.SoTien);
}
//=================================
void NhapDSTK(TK a[],int &n)
{
    printf("\n Nhap so luong tai khoan:");scanf("%d",&n);
    for(int i=0;i<n;i++)
    Nhap1TK(a[i]);
}
//=================================
void XuatDSTK(TK a[],int n)
{
    for(int i=0;i<n;i++)
    Xuat1TK(a[i]);
}

//================viet tat ca vao file
void GhiFile(char *duongdan,TK a[],int n)
{
    FILE *f=fopen(duongdan,"wb");
    if(!f)
    {
        printf("\nkhong ghi duoc!!!");
        return;
    }

        for(int i=0;i<n;i++)
        if(a[i].SoTien>5) fwrite(&a[i], sizeof(TK), 1, f);
    fclose(f);
    printf("\n ghi file thanh cong");
}


int main()
{

    TK x;TK a[max];
    int n;
    char X[10];
    NhapDSTK(a,n);XuatDSTK(a,n);printf("\n");


    GhiFile("D:/toni.txt",a,n);
}