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)
更新:2007 年 11 月
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
*/