Exclude last element in a loop

Question

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Dear Friend,

I have a loop in my app. Code is following-

C#

foreach (DataRow dr in dt.Rows)
{
ColorNames +=dr["ColorName"].ToString() + "\n";
}

But i don't want to add "\n" at the last datarow.
Any suggestion how to do it?

Regards
Saumitra.

Posted 10-May-12 0:47am

Saumitra Kumar Paul

Updated 10-May-12 0:56am

v2

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5 solutions

Solution 1

This code may help you

C#

foreach (DataRow dr in dt.Rows)
        {
            ColorNames += ColorName + "\n";
        }
        ColorNames = ColorNames.Substring(0, (ColorNames.Length - 1));

Posted 10-May-12 0:51am

Sudheer Nimmagadda

Comments

CodeHawkz 10-May-12 7:28am

Sudheer, your solution is the optimal in this kind of scenario, but you have to add a simple if clause for it to be error prone.

if (ColorNames.length > 0)
ColorNames = ColorNames.Substring(0, (ColorNames.Length - 1));

or

if (dt.Rows.Count > 0)
ColorNames = ColorNames.Substring(0, (ColorNames.Length - 1));

would do the trick :)

Hope this helps

Sudheer Nimmagadda 10-May-12 9:43am

PasanRatnayake, your right, Thanks you

Solution 6

return string.Join("\n", dr.Rows.Select(row => row["ColorName"].ToString()).ToArray());

Something like that should work, if you're using a version where System.Linq extensions are available.

Posted 10-May-12 3:46am

BobJanova

Solution 3

What about:

C#

foreach (DataRow dr in dt.Rows)
{
  if(dt.Row.IndexOf(dr) < dt.Rows.Count-1)
  ColorNames +=dr["ColorName"].ToString() + "\n";
}

Posted 10-May-12 1:59am

Zoltán Zörgő

Comments

Pete O'Hanlon 10-May-12 8:06am

Two things. First, you are doing a lot of conditional checks in here as you go through each loop iteration. Second, you haven't got the last row.

Zoltán Zörgő 10-May-12 8:09am

"Exclude last element in a loop" means for me to exclude last row. Or not?

Pete O'Hanlon 10-May-12 8:45am

If you read his question it states he only wants to exclude the last \n.

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CPallini · Accepted Answer · 2012-05-10T02:03:00

Solution 4

Well, you know, foreach is not the only way for iterating:

C#

int i;
for (i = 0; i < dt.Rows.Count - 1; i++)
{
  DataRow dr = dt.Rows[i];
  ColorNames += dr["ColorName"].ToString() + "\n";
}
ColorNames += dt.Rows[i].dr["ColorName"];

Posted 10-May-12 2:03am

CPallini

Updated 10-May-12 2:04am

v2

Comments

Saumitra Kumar Paul 10-May-12 8:10am

Your solution is excellent. My vote is 5/5.

Pete O'Hanlon · Accepted Answer · 2012-05-10T02:12:00

You have lots of answers to play with here, but nobody has addressed the fact that you may be doing lots of string concatenations here. In general, if you are going to be appending more than a couple of elements together, you should look into using a StringBuilder. What you would end up with (using CPallin's excellent suggestion) is:

C#

StringBuilder sb = new StringBuilder();
int count = dt.Rows.Count - 1;
for (int i = 0; i < count; i++)
{
  sb.AppendFormat("{0}\n", dt.Rows[i]["ColorName"].ToString());
}
sb.Append(dt.Rows[count]["ColorName"].ToString());
ColorNames = sb.ToString();

Another thing to consider is whether you should be using \n or Environment.NewLine. As I'm not 100% sure what your requirements are there, I'll leave it to you to investigate which is best suited to your needs.