#include <iostream>
using namespace std;

struct xx                                //定义一个名为xx的结构体
{
    char no[10];                         //编号
    char seimei[22];                     //姓名
    char seibenn[5];                     //性别
    char dennwa[15];                     //电话
    char email[30];                      //电子信箱
};

int caidan()                              //菜单
{
   int i;                                 //判断条件
   system("cls");                         //清屏
   cout<<"\t\t\t\t  通讯录\n";
   cout<<"--------------------------------------------------------------------------------";
   cout<<"1.浏览    ";
   cout<<"2.添加    ";
   cout<<"3.修改    ";
   cout<<"4.查找    ";
   cout<<"5.删除    ";
   cout<<"6.退出";
   cout<<"\n--------------------------------------------------------------------------------";
   cout<<"我要选择:";
   cin>>i;                                //键入i的值,既选择执行入口
   return i;                              //将i的值返回到main
}

int tj()                                  //添加信息函数
{
    int i;                                 //条件判断
    FILE *fp;                              //文件指针fp
    if((fp=fopen("xinxi.txt","ab"))==NULL)
    {
        cout<<"文件写入失败!按任意键返回主菜单";
        system("Paesu");
        return ;
    }
    cout<<"输入编号:";
    cin>>xx.no;
    cout<<"输入姓名:";
    cin>>xx.seimei;
    cout<<"输入性别:";
    cin>>xx.seibenn;
    cout<<"输入电话:";
    cin>>xx.dennwa;
    cout<<"输入电子信箱:";
    cin>>xx.email;
    fwrite(&xx,sizeof(xx),1,fp);
    fclose fp;
    cout<<"\n文件信息添加完毕,现在?\n\n1.继续添加\t2.返回主菜单\t3.退出";
    cin>>i;
    while(i!=1||i!=2||i!=3)
    {
        cout<<"请输入1,2,3.";
        break;
    }
    if(i==1)
        int tj();
    if(1==2)
        return ;
    if(i==3)
        return 0;
}


int main()
{
    switch(caidan())
    {
    case '1':return 0;break;
    case '6':return 0;break;
    }
    return 0;
}

哎呀,我知道了
忘记定义结构体了