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関数「BY VAL」に「参照型」を渡しています。関数では、foreach ループで参照型を変更しようとしています。

次に、呼び出し元になると、渡したオブジェクトが更新されません。しかし、更新されたオブジェクトを返します。

この問題の例を以下に示します。

数分かけて、なぜこのようなことが起こっているのか、誰かが私を助けてくれますか?

以下はメソッドGetStudents()、FilterStudents()、classes、Student、Teacher、SSCClass、

SSCClass - Teachers 配列が含まれています。教師 - 生徒の配列が含まれます。

    public void GetStudents()
    {

        Student[] sscStudentsOne = new Student[] { new Student { V_SId = 1, V_SName = "Kumar" }, new Student { V_SId = 2, V_SName = "Varun" }, new Student { V_SId = 3, V_SName = "Murthy" } };

        Student[] sscStudentsTwo = new Student[] { new Student { V_SId = 4, V_SName = "Sathya" }, new Student { V_SId = 5, V_SName = "Krishna" }, new Student { V_SId = 6, V_SName = "Bindu" } };


        Teacher[] sscTeachers = new Teacher[] { new Teacher { V_tId = 1, V_tName = "Jyothi", V_Students = sscStudentsOne }, new Teacher { V_tId = 2, V_tName = "Srinivas", V_Students = sscStudentsTwo } };

        SSCClass objSSCClass = new SSCClass();
        objSSCClass.V_sscTeachers = sscTeachers;

        SSCClass objSSCClassFiltered =  FilterStudents(objSSCClass);
        // Problem :-
        // in objSSCClass Kumar is getting removed but Sathya from second teachere is not getting removed.
        // in objSSCClassFiltered  Kumar and Sathya are Getting removed as we did.
        // We need objSSCClass object to be updated successfully ..  as we can not return this to caller method in my project.

    }
    public SSCClass FilterStudents(SSCClass objSSCClasstobeFiltered)
    {

        foreach (Teacher item in objSSCClasstobeFiltered.V_sscTeachers)
        {

            // here a method will be called and does the below
            // removes Students based on some criteria
            // Say,
            // Remove Student Kumar  from first teacher.
            // Remove Student Sathya from second teacher

        }

        // after filtering Students return the SSC Class object

        return objSSCClasstobeFiltered;
    }

    public class Student
    {

        int v_sId;

        public int V_SId
        {
            get { return v_sId; }
            set { v_sId = value; }
        }

        string v_SName;

        public string V_SName
        {
            get { return v_SName; }
            set { v_SName = value; }
        }
    }

    public class Teacher
    {

        int v_tId;

        public int V_tId
        {
            get { return v_tId; }
            set { v_tId = value; }
        }


        string v_tName;

        public string V_tName
        {
            get { return v_tName; }
            set { v_tName = value; }
        }


        Student[] v_Students;

        public Student[] V_Students
        {
            get { return v_Students; }
            set { v_Students = value; }
        }
    }


    public class SSCClass
    {
        Teacher[] v_sscTeachers;

        public Teacher[] V_sscTeachers
        {
            get { return v_sscTeachers; }
            set { v_sscTeachers = value; }
        }

    }
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1 に答える 1

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ForeachRef を更新して、新しいものを作成してから更新することはできません。

Foreach (Student s in student_list)
{...
   S s2 = s;
     s2 = newval;
...}
于 2013-05-05T04:13:46.373 に答える