C# out Keyword

In C#, out keyword 是argument传值变成passed by reference. out keyword 在同时返回多个值时很有用.

与ref keyword 相似. 若是使用out keyword传argument, 那么在method 的definition 和 使用时都需要家out keyword.

Async methods can't use out keyword.

Differences between out keyword and ref keyword:

ref requires that variable be initialized before it is passed.

 class OutReturnExample
 {
     static void Method(out int i, out string s1, out string s2)
     {
         i = ;
         s1 = "I've been returned";
         s2 = null;
     }
     static void Main()
     {
         int value;
         string str1, str2;
         Method(out value, out str1, out str2);
         // value is now 44
         // str1 is now "I've been returned"
         // str2 is (still) null;
     }
 }