901225-如何通过引用从方法返回对象? [英] 901225 - how to return an object from a method by reference?

问题描述

在以下代码中，如何将查找"从C ++转换为C#?
换句话说，如何在C#中返回对对象的引用?

 结构 MyStruct
{
     int  id;
    ...
} list [] =
{
    ...
};

MyStruct& find( int  id)
{
     for ( int  i =  0 ; i< ; _countof(list); i ++)
        如果(id == list [i] .id)
            返回列表[i]；
    静态 MyStruct empty = { 0 ，...};
    返回为空；
} 

解决方案

http: //msdn.microsoft.com/zh-CN/library/14akc2c7.aspx [ http://msdn.microsoft.com/en-us/library/14akc2c7 (v = vs.71).aspx [

或者，可以尝试以下代码

 结构 MyStruct {
    公共  int  ID；
       
    公共 MyStruct( int  id){
        Id = id;
    }
}

 var  list = 新 List< mystruct>();

// 将项目添加到列表
list.Add(新 MyStruct( 5 ));
list.Add(新 MyStruct( 10 ));
// 要查找与ID匹配的列表项，请说5使用带有谓词的Find方法
MyStruct foundStruct = list.Find(myStruct = >  myStruct.Id ==  5 );  

in the following code, how do u convert ''find'' from C++ to C#?
in another words, how to return a reference to an object in C#?

struct MyStruct
{
    int id;
    ...
} list[]=
{
    ...
};

MyStruct &find(int id)
{
    for (int i=0; i<_countof(list); i++)
        if (id == list[i].id)
            return list[i];
    static MyStruct empty={0,...};
    return empty;
}

解决方案

http://msdn.microsoft.com/en-us/library/14akc2c7.aspx[^]

Use the ref keyword or (out in your case because you want to (possible) reassign the pointer (when you return the empty struct))

http://msdn.microsoft.com/en-us/library/14akc2c7(v=vs.71).aspx[^]

Btw: I think this pattern is not "state of the art" for .net.

As an alternative, the following code may be tried

struct MyStruct {
    public int Id;
       
    public MyStruct(int id){
        Id=id;
    }
}

var list = new List<mystruct>();
	
//add items to the list
list.Add(new MyStruct(5));
list.Add(new MyStruct(10));
//To find an item of list matching an Id say 5 use the Find method with a predicate
MyStruct foundStruct = list.Find(myStruct => myStruct.Id == 5);

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