Concatenating string with String Builder?

Question

I want to generate a string with a format

'abc','avc',abc','avc',abc','avc','abc','avc',abc','avc',abc','avc','abc','avc'

The value can be anything or it can be empty.This is my code

        string sep = "";
        StringBuilder sb = new StringBuilder();
        foreach(var l in label.Rows)
        {
            sb.Append(sep).Append(l.Text);
            sep = ",''";
        }

this returns me

abc,''abc,''abc,''abc,''abc,''abc,''abc,''abc,''abc,''abc,''abc,''abc,''abc,''abc,''abc

any help will be appreciated.

And what problem did you get with that code?

Steve
– Steve

2018-09-03 13:28:08 +00:00
Commented Sep 3, 2018 at 13:28 — Steve
– Steve, Commented Sep 3, 2018 at 13:28
You really want your string to start with ,?

Magnus
– Magnus

2018-09-03 13:30:01 +00:00
Commented Sep 3, 2018 at 13:30 — Magnus
– Magnus, Commented Sep 3, 2018 at 13:30
"I think I can't make the logic" What is the logic?

Tim Schmelter
– Tim Schmelter

2018-09-03 13:30:09 +00:00
Commented Sep 3, 2018 at 13:30 — Tim Schmelter
– Tim Schmelter, Commented Sep 3, 2018 at 13:30
@Magnus it doesn't

Jeroen van Langen
– Jeroen van Langen

2018-09-03 13:30:37 +00:00
Commented Sep 3, 2018 at 13:30 — Jeroen van Langen
– Jeroen van Langen, Commented Sep 3, 2018 at 13:30
@J.vanLangen no? ,'abc','avc',abc......

Magnus
– Magnus

2018-09-03 13:31:16 +00:00
Commented Sep 3, 2018 at 13:31 — Magnus
– Magnus, Commented Sep 3, 2018 at 13:31

Steve · Accepted Answer · 2018-09-03 13:43:57Z

4

Of course using Linq will be simpler and more readable, but if you want to know what has gone wrong in your code then

// Start with the initial quote
string sep = "'";
StringBuilder sb = new StringBuilder();
foreach(var l in label.Rows)
{
    sb.Append(sep).Append(l.Text);
    // Quote before and after the comma
    sep = "','";
}
// You need an additional quote to close the string if there is any
if(sb.Length > 0)
   sb.Append("'");

Consider also that StringBuilder is not always faster than a simple concatenation. If this code is performance sensitive I would try to measure what happen if you use a single sb.Append(sep + l.Text) instead of calling two times the Append method

edited Sep 3, 2018 at 13:43

answered Sep 3, 2018 at 13:36

Steve

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Comments

Tim Schmelter · Accepted Answer · 2018-09-03 13:33:44Z

3

More simple with LinQ and method Join

string s = string.Join(",", label.Rows.Select(l => $"'{l.Text}'"));

edited Sep 3, 2018 at 13:33

Tim Schmelter

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answered Sep 3, 2018 at 13:27

Antoine V

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