To get a comma separated list For Loop or String.Join().Which is Best?

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Hi Friends,

I would like to get a comma separated list. I have two approaches.
First one is normal For loop and second one is String.Join() Method.
Considering the performance which will be the best approach.

C#

StringBuilder KeyTmsList = new StringBuilder();
for (int i = 0; i < dsKeytms.Tables[0].Rows.Count; i++)
 {
   KeyTmsList = KeyTmsList.Append("'" + dsKeytms.Tables[0].Rows[i]["KEY_TMS"].ToString() + "'" + ",");
 }
  KeyTmsList = KeyTmsList.Remove(KeyTmsList.Length - 1, 1);

C#

string KeyTmsList = string.Join(",", dsKeytms.Tables[0].AsEnumerable().Select(r => r.Field<string>("KEY_TMS")).ToArray());

Posted 12-Apr-15 22:12pm

jinesh sam

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samitrpatel · Accepted Answer · 2015-04-12T22:19:00

Solution 1

I think string.join() is the best option.

Posted 12-Apr-15 22:19pm

samitrpatel

Comments

jinesh sam 13-Apr-15 5:31am

Hi Samit,
Can you give any valid reason for your selection.

samitrpatel 13-Apr-15 6:09am

You should use string.Join() because:

1) it's much more readable, maintainable and easy on the eyes.

2) it uses a StringBuilder internally already, so it's very efficient ( you can confirm yourself using Reflector).

string.Join() uses a StringBuilder for the general case of an IEnumerable<t> input. If you already have an array on the other hand it uses some voodoo magic (including FastAllocateString() and UnSafeCharBuffer) to be even faster.

jinesh sam 13-Apr-15 6:56am

Thanks:)

samitrpatel 13-Apr-15 7:55am

always welcome.

BillWoodruff · Accepted Answer · 2015-04-13T01:44:00

A comparison of 'StringBuilder and 'Join is difficult here because you are using different methods of "composing" the contents of your Tables[0] (its Rows) into an enumerable form for manipulation: in the second example you are using Linq instead of a for-loop.

So, in some ways you are really asking about comparing using Linq to using a 'for-loop.

There is a detailed discussion of using 'Join vs. 'StringBuilder here: [^] which you might find useful.

Also see the discussion and timing results here: [^].

My reading of the above discussions suggests that 'Join and 'StringBuilder are about equally performant, but I believe that for your case you'd have to do some timing.

The special case of 'Join using 'StringBuilder internally appears to be true only under these conditions:

1. .NET 4.0 or later

2. the argument to 'Join is an IEnumerable<string>

However, when the arguments to 'Join is an Array, 'Join uses "FastAllocateString() and UnSafeCharBuffer)" ... see the second link above for the source of this comment.