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POSerialize a HashSet<String> with LinQ
 

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    <p>I'd like to take a <code>HashSet&lt;String&gt;</code> and elegantly convert it to a string. I can iterate like so:</p> <pre><code>HashSet&lt;String&gt; words = new HashSet&lt;string&gt;() { "alpha", "beta", "delta" }; string joined = ""; foreach (var w in words) joined += w + ","; if(joined.Length &gt; 0) joined = joined.SubString(0,joined.Length-1); // remove final comma </code></pre> <p>Is there a <code>LinQ</code> way to do this elegantly and efficiently?</p> <p>The only way I can think of doing this is by converting it to an array first:</p> <pre><code>HashSet&lt;String&gt; words = new HashSet&lt;string&gt;() { "alpha", "beta", "delta" }; string joined = String.Join(",",words.ToArray()); </code></pre> <p>But, then I'm doing a double conversion. Would there be some handy-dandy LinQ expression that's efficient and clear?</p> <p><strong>ANSWER 1 (from marr's idea)</strong></p> <pre><code>public static string JoinItems(this IEnumerable&lt;string&gt; items, string joiner) { StringBuilder sb = new StringBuilder(""); foreach (var i in items) sb.AppendFormat("{0}{1}",i,joiner); if(sb.Length&gt;0) return sb.Remove(sb.Length - joiner.Length, joiner.Length).ToString(); else return sb.ToString(); } </code></pre> <p><em>ANSWER 2 using an Enumerator (from Martin's solution)</em></p> <pre><code>public static string JoinItems&lt;T&gt;(this IEnumerable&lt;T&gt; items, string delim) { var sb = new StringBuilder(); var i = items.GetEnumerator(); if (i.MoveNext()) { sb.Append(i.Current); while (i.MoveNext()) { sb.Append(delim); sb.Append(i.Current); } } return sb.ToString(); } </code></pre>
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    1. COPerhaps you are unaware of the overload of string.Join that takes an enumerable? (Which includes HashSet<string>)
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      1. USKirk Woll
    2. CO@Kirk - Only 4.0 has that overload. 3.5 does not. http://msdn.microsoft.com/en-us/library/system.string.join(v=VS.90).aspx
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    3. COYep, using 3.5 still.
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