？？ 运算符 和三元运算符

如果 ?? 运算符的左操作数非 null，该运算符将返回左操作数，否则返回右操作数。

示例：

 

// nullable_type_operator.cs
using System;
class MainClass
{
static int? GetNullableInt()
{
return null;
}
static string GetStringValue()
{
return null;
}
static void Main()
{
// ?? operator example.
int? x = null;
// y = x, unless x is null, in which case y = -1.
int y = x ?? -1;
// Assign i to return value of method, unless
// return value is null, in which case assign
// default value of int to i.
int i = GetNullableInt() ?? default(int);
string s = GetStringValue();
// ?? also works with reference types.
// Display contents of s, unless s is null,
// in which case display "Unspecified".
Console.WriteLine(s ?? "Unspecified");
}
}

三元运算符 举例如下

string resultString = (myInteger < 10) ? "Less than 10" : "Greater than or equal to 10";