Why is my dictionary data being overwritten?-CodePudding

not sure what is going on here. My data items I store in the first dictionary entry get overwritten when I go to update data to the second entry. The dictionary's first entry is acting like it is using a reference to the original object so when i change it all instances in the dictionary change. the first set of data is 1,2,3 and stored in partitionInfo[0]. when i got to store the next set of data, 4,5,6 partitionInfo[1] updates but parttionInfo[0] updates those values as well. so i end up with my two dictionary entries have the same set of data. however the strings stay unique. representation code of what i am seeing

private void button1_Click(object sender, EventArgs e)
    {
        Datum dataItems = new Datum();
        Partition partitionItem = new Partition();
        LRU lruItem = new LRU();

        dataItems.minData = "1";
        dataItems.maxData = "2";
        dataItems.avgData = "3";
        partitionItem.partitionInfo.Add("Entry1", dataItems);


        dataItems.minData = "4";
        dataItems.maxData = "5";
        dataItems.avgData = "6";
        partitionItem.partitionInfo.Add("Entry2", dataItems);

        lruItem.lruInfo.Add("Parent", partitionItem);

    }


public class LRU
{
    public Dictionary<string, Partition> lruInfo = new Dictionary<string, Partition>();
}

public class Partition
{
  public Dictionary<string, Datum> partitionInfo = new Dictionary<string, Datum>();
}

public class Datum
{
    public string minData;
    public string maxData;
    public string avgData;

}

CodePudding user response：

You are overwriting your values beginning with the line dataItems.minData = "4"; Just because you've stored the value in Entry1 it doesn't "lock it away" as I suspect you think.

You original comment:

The dictionary's first entry is acting like it is using a reference to the original object so when I change it all instances in the dictionary change

You were close to grasping the error in your code...

See the fixed code:

Partition partitionItem = new Partition();

Datum dataItems = new Datum(); 
// **** It's better to declare your variables just
// before you use them to make it clearer ****
dataItems.minData = "1";
dataItems.maxData = "2";
dataItems.avgData = "3";
partitionItem.partitionInfo.Add("Entry1", dataItems);


dataItems = new Datum(); // **** ADDED LINE ****

// We now have a new block of memory containing a `Datum` 
// the one above is left untouched
dataItems.minData = "4";
dataItems.maxData = "5";
dataItems.avgData = "6";
partitionItem.partitionInfo.Add("Entry2", dataItems);

LRU lruItem = new LRU(); **** Moved, as before ****
lruItem.lruInfo.Add("Parent", partitionItem);