Quản Lý Sinh Viên (Mảng)

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
/*
Code by Huy Hung
Email: huyhung1994@gmail.com
Created 01:00 20/02/2014
Using C-Free 5.0
*/
struct sinhvien{
    char ten[50];
    int tuoi;
    float dtb;
};
typedef sinhvien svien;
svien sv[50];

char name[30];
int i,j,n,vt;
//Nhap danh sach
void input(int &n){
    system("cls");
    printf("Nhap so luong sinh vien: "); scanf("%d",&n);
    printf("\n=============Input=============");
    for(i=0;i<n;i++){
        printf("\nNhap thong tin cho nguoi thu %d\n",i+1);
        fflush(stdin);
        printf(" Ho va ten: ");
        gets(sv[i].ten);
        printf(" Tuoi: ");
        scanf("%d",&sv[i].tuoi);
        printf(" Diem trung binh: ");
        scanf("%f",&sv[i].dtb);
        printf("==============================\n");
    }
}
//In danh sach
void output(int &n){
    system("cls");
    printf("\n\t\t+++++++++ QUAN LY SINH VIEN +++++++++\n");
    printf("\n\t\t STT\t TEN \t Tuoi\tDiem TB\n");
    for(int i=0;i<n;i++){
        printf("\t\t%3d   %s\t%d\t%3.2f\n",i+1,sv[i].ten,sv[i].tuoi,sv[i].dtb);
     }
     printf("\n\n");
}
//Tim kiem sinh vien
int search(char name[30]){
    fflush(stdin);
    printf(" Nhap ten sinh vien: ");
    gets(name);
    for(i=0;i<n;i++){
         if(strcmp(sv[i].ten,name)==0){
            return(i); //Tim thay sinh vien. Tra ve vi tri cua svien do.
         }
    }
    return(-1); //Khong tim thay sinh vien.
}
//Them sinh vien
int Add(int vt, int &n){
    //Tang kich thuoc mang
    for(i=n;i>vt;i--){
        sv[i]=sv[i-1];
    }
    //Chen thong tin sinh vien
    fflush(stdin);
    printf("Nhap ho ten svien muon them: ");
    gets(sv[vt].ten);
    printf(" Nhap tuoi: ");
    scanf("%d",&sv[vt].tuoi);
    printf(" Diem trung binh: ");
    scanf("%f",&sv[vt].dtb);
    printf("Da them thanh cong.\n");
    n++;
}
//Ham Xoa
int Del(int vt, int &n){
    int i;
    for(i=vt;i<n-1;i++){
        sv[i]=sv[i+1];
    }
    printf("Da xoa thanh cong\n");
    n--;
}

//Ham chinh
int main(){
    struct sinhvien sv[100];
    int m;
    system("color a");
    do{
    system("cls");
    printf("\n\n\tMenu: Thao tac");
    printf("\n\t\t\t\tCode by Huy Hung");
    printf("\n1. Nhap danh sach.");
    printf("\n2. In danh sach");
    printf("\n3. Them sinh vien truoc svien da biet.");
    printf("\n4. Xoa sinh vien");
    printf("\n5. Thoat.");
    printf("\n\n Ban chon: "); scanf("%d",&m);
    switch(m){
      case 1: input(n); system("pause");break;
      case 2: output(n);system("pause");break;
      case 3: output(n);
              vt=search(name);
              if(vt!=-1){
                    Add(vt,n);
                    output(n);
                }else printf("Khong tim thay sinh vien.\n");
                system("pause");
               break;

      case 4: output(n);
              int vt=search(name);
              if(vt!=-1){
                   Del(vt,n);
                    output(n);
                }else printf("Khong tim thay sinh vien.\n");
                system("pause");
                break;

      case 5: printf("Xin chao va hen gap lai.\n"); break;
      default: printf("Ban da chon sai chuc nang.\nVui long chon lai.\n"); system("pause");break;
      };
    }while(m!=5);

}