这称为合并。

当this.teacher为NULL时，返回一个新的teacher（）对象;

??是空合并运算符 - microsoft reference [ ^ ]



所以一段代码本质上是说返回当前的teacher实例，或者如果当前实例为null，则创建一个

你的示例代码是惯用的C＃代码来说

  if （teacher ==  null ） //  这是*之前的部分*??合并运算符 
 {
 teacher =  new  Teacher（）;  //  这是*之后的部分*合并运算符 
} 
返回老师; 

或

 返回老师！=  null ？老师:(老师= 新老师（））; 

干杯

Andi

Hello guys, could you tell me what is this? I saw this in an article.

public Person Teacher
{
    get
    {
        return this.teacher ?? (this.teacher = new Teacher());
    }
}

I have no idea what is this??

This is called coalescing.
When this.teacher is NULL return a new teacher() object;

?? Is the null coalescing operator - microsoft reference[^]

So the piece of code is essentially saying return the current instance of teacher, or if the current instance is null create one

Your example code is idiomatic C# code to say

if (teacher == null)        // this is the part *before* the "??" coalescing operator
{
   teacher = new Teacher(); // this is the part *after* the "??" coalescing operator
}
return teacher;

Or

return teacher != null ? teacher : (teacher = new Teacher());

Cheers
Andi