声明的时候,值类型后面加个问号,判断的时候就可以都用null,如: public class V { public int? aa; public string bb; public V() { } } V v = new V(); if (v.aa == null) Response.Write("aa<br>"); if (v.bb == null) Response.Write("bb<br>");
比如有个属性 /// <summary> 登录次数 </summary> public int LoginNum { get { return _loginNum; } set { _loginNum = value; } } 就算我没有赋过值他也会默认成0
nullable
引用
null
用string.IsNullOrEmpty()可否
public class V
{
public int? aa;
public string bb; public V()
{ }
} V v = new V();
if (v.aa == null)
Response.Write("aa<br>");
if (v.bb == null)
Response.Write("bb<br>");
/// <summary> 登录次数 </summary>
public int LoginNum
{
get { return _loginNum; }
set { _loginNum = value; } }
就算我没有赋过值他也会默认成0