How do I optimize nested foreach loops

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I have two foreach loops. One Foreach in other loop. How do i optimize those nested foreach loops

What I have tried:

C#

foreach (var t in ValidBCodes)
{
     foreach (var y in InsertRows)
     {
          var newRow = ds.Tables["FACT"].NewRow();
          newRow["S_ID"] = DestinationScenarioId;
          newRow["B_ID"] = t;
          newRow["G_ID"] = y["GLOBALFIELD_ID"];
          newRow["AMOUNT"] = y["AMOUNT"];

          ds.Tables["FACT"].Rows.Add(newRow);
      }
}

Posted 13-Mar-16 9:51am

MYQueries1

Updated 13-Mar-16 11:25am

CHill60

v4

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CHill60 13-Mar-16 16:15pm

What are ValidBCodes and InsertRows and how are they related?

PIEBALDconsult 13-Mar-16 16:31pm

Usually by not using foreach.
About all I can recommend is to not search for the table each time -- make a local variable to hold a reference to ds.Tables["FACT"] and use that.
You may also want to use column ordinals as well -- rather than column names.

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Patrice T · Answer 1 · 2016-03-13T10:59:00

Solution 1

~~If newRow can't be reused, there is no optimization possible.~~
If newRow can be reused, I would rewrite the code this way.

C#

var newRow = ds.Tables["FACT"].NewRow();
foreach (var y in InsertRows)
{
	newRow["S_ID"] = DestinationScenarioId;
	newRow["G_ID"] = y["GLOBALFIELD_ID"];
	newRow["AMOUNT"] = y["AMOUNT"];
	foreach (var t in ValidBCodes)
	{
		newRow["B_ID"] = t;
		ds.Tables["FACT"].Rows.Add(newRow);
	}
}

[update]
If newRow can't be reused, simply swapping the loops allow the compiler to see that y["GLOBALFIELD_ID"] and y["AMOUNT"] are constant in the inner loop and move the reading of these values outside of inner loop.

C#

foreach (var y in InsertRows)
{
     foreach (var t in ValidBCodes)
     {
          var newRow = ds.Tables["FACT"].NewRow();
          newRow["S_ID"] = DestinationScenarioId;
          newRow["B_ID"] = t;
          newRow["G_ID"] = y["GLOBALFIELD_ID"];
          newRow["AMOUNT"] = y["AMOUNT"];
 
          ds.Tables["FACT"].Rows.Add(newRow);
      }
}

Posted 13-Mar-16 10:59am

Patrice T

Updated 13-Mar-16 19:36pm

v3

Comments

CHill60 13-Mar-16 17:14pm

Actually that was me making a mistake when I reformatted the OP's code :blush:
Sorry @VijayAkkaladevi

Patrice T 13-Mar-16 17:16pm

Ok

Sascha Lefèvre 13-Mar-16 17:16pm

A DataRow-object can't be reused to add multiple new DataRows to a DataTable, you get an ArgumentException "This row already belongs to this table". Please don't base solutions on assumptions, test them if you're not sure about it.

Patrice T 13-Mar-16 17:22pm

Sorry, need to have C# to test :)

Sascha Lefèvre 13-Mar-16 17:25pm

There you go:
https://www.visualstudio.com/en-us/products/visual-studio-community-vs.aspx
:p

Patrice T 13-Mar-16 17:30pm

I have an allergy to C family of languages :)

MYQueries1 14-Mar-16 5:04am

Is there any way i can optimize my code.
foreach (var y in InsertRows)
{
foreach (var t in ValidBCodes)
{
var newRow = ds.Tables["FACT"].NewRow();
newRow["S_ID"] = DestinationScenarioId;
newRow["B_ID"] = t;
newRow["G_ID"] = y["GLOBALFIELD_ID"];
newRow["AMOUNT"] = y["AMOUNT"];

ds.Tables["FACT"].Rows.Add(newRow);
}
}

Patrice T 14-Mar-16 5:19am

This is the optimisation