static void Main6(string[] args)
{
object up = new UPMaster()
{
Date = new Date()
{
Like = int.MaxValue
}
};
var dataValue1 = up.GetType().GetProperty("Date").GetValue(up);
var likeValue1 = dataValue1.GetType().GetProperty("Like").GetValue(dataValue1);
// dynamic 表示在运行时解析其操作的对象
var likeValue2 = ((dynamic)up).Date.Like;
// 性能对比
Random rand = new Random();
List <UPMaster> ups = Enumerable.Range(0, 1000_0000).Select(x => new UPMaster()
{
Date = new Date()
{
Like = rand.Next(10_0000)
}
}).ToList();
public static void Main4(string[] args)
{
var up = new UPMaster()
{
Date = new Date()
{
Like = 2
}
};
// 方法一：
var like1 = up.Date.Like;
// 方法二：
var like2 = 0;
if (up != null && up.Date != null && up.Date.Like.HasValue)
{
like2 = up.Date.Like.Value;
}
// 方法三：
var like3 = up?.Date?.Like ?? 0;
// 注意：
// ?? 运算符的优先级高于 ?：
int?coin1 = 1;
int?coin2 = 2;
var like4 = coin2 > coin1 ? coin2 : coin1 ?? 0;
var like5 = (coin2 > coin1 ? coin2 : coin1) ?? 0;
WriteLine(like4);
WriteLine(like5);
}
