如何：了解向方法传递结构和向方法传递类引用之间的区别（C# 编程指南）

本示例演示在向方法传递结构时，传递的是该结构的副本，而在传递类实例时，传递的是一个引用。

本示例的输出表明：当向 ClassTaker 方法传递类实例时，只更改类字段的值。但是向 StructTaker 方法传递结构实例并不更改结构字段。这是因为向 StructTaker 方法传递的是结构的副本，而向 ClassTaker 方法传递的是对类的引用。

示例

class TheClass{ public string willIChange;}struct TheStruct{ public string willIChange;}class TestClassAndStruct{ static void ClassTaker(TheClass c) { c.willIChange = "Changed"; } static void StructTaker(TheStruct s) { s.willIChange = "Changed"; } static void Main() { TheClass testClass = new TheClass(); TheStruct testStruct = new TheStruct(); testClass.willIChange = "Not Changed"; testStruct.willIChange = "Not Changed"; ClassTaker(testClass); StructTaker(testStruct); Console.WriteLine("Class field = {0}", testClass.willIChange); Console.WriteLine("Struct field = {0}", testStruct.willIChange); // Keep the console window open in debug mode. Console.WriteLine("Press any key to exit."); Console.ReadKey(); }}/* Output: Class field = Changed Struct field = Not Changed*/

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