void insert_account(FILE *fp)//新建账户模块函数
{
    BANKACCOUNT newaccount;

    printf("请输入账号信息\n");
    printf(">>账号:");
    scanf("%d",&(newaccount.account));
    printf(">>密码:");
    scanf("%d",&(newaccount.key));
    printf(">>姓名:");
    scanf("%s",newaccount.name);
    printf(">>余额:");
    scanf("%f",&(newaccount.balance));
    fseek(fp,0L,SEEK_END);
    fprintf(fp,"%d %d %s %.2f\n",newaccount.account,newaccount.key,newaccount.name,newaccount.balance);
}