Change the value in the list without changing the variable

Question

Change the value in the list without changing the variable

Алексей Куликов 21

Hello. I have a list. I want to change the last element in it. But without changing the object and / or variable. And when you change an item in the list, the variable also changes. How to do it?

    class ClassM
    {
        public int value { get; set; }
    }

        ClassM dimTemp;
        List<ClassM> lstData = new List<ClassM>();


lstData.LastOrDefault().value = dimTemp.value + lstData.LastOrDefault().value;

I need the value in dimTemp not to change. And it changes.

Viorel 126.9K Reputation points

2021-04-10T11:42:30.057+00:00

Currently dimTemp is unassigned or null, the list is empty, and the statement does not work. Show an example that works.

Answer accepted by question author

Ken Tucker 5,866

I dont think you posted all the code. I suspect you added dimTemp to the list. So the last item in the list is dimTemp and updating the item in the list will make it to the variable. Add a clone of dimTemp to the list if you do not want the dimTemp variable to update.

class ClassM:ICloneable
{
    public int value { get; set; }
    public object Clone()
    {
        return new ClassM()
        {
            value = this.value
        };
    }
}


        ClassM dimTemp;
        List<ClassM> lstData = new List<ClassM>();
        dimTemp = new ClassM();
        dimTemp.value = 1;
        lstData.Add((ClassM)dimTemp.Clone());
        Console.WriteLine(dimTemp.value);
        lstData.LastOrDefault().value = dimTemp.value + lstData.LastOrDefault().value;

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Viorel 126.9K Reputation points

2021-04-10T11:42:30.057+00:00

Currently dimTemp is unassigned or null, the list is empty, and the statement does not work. Show an example that works.

Answer 1

Алексей Куликов 21

ClassM = dimTemp;
List<ClassM> lstData = new List<ClassM>();
void Start()
{
dimTemp = new ClassM () { value = 1 };

AddMetod();
AddMetod();

ChangeMetod();
}

void AddMetod()
{
dimTemp = new ClassM (){value = 1};
lstData .Add(dimTemp);
}
void Changemetod()
{

lstData.LastOrDefault().value = dimTemp.value + lstData.LastOrDefault().value;

}

dimTemp also becomes 2. Although it should remain 1.

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Change the value in the list without changing the variable

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