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.
1 class OutReturnExample 2 { 3 static void Method(out int i, out string s1, out string s2) 4 { 5 i = 44; 6 s1 = "I‘ve been returned"; 7 s2 = null; 8 } 9 static void Main() 10 { 11 int value; 12 string str1, str2; 13 Method(out value, out str1, out str2); 14 // value is now 44 15 // str1 is now "I‘ve been returned" 16 // str2 is (still) null; 17 } 18 }
原文：http://www.cnblogs.com/Dylan-Java-NYC/p/5870451.html