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POSplit array into size limited CSV strings
 

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  1. POSplit array into size limited CSV strings
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    <p>I am looking for an efficient way to convert a large int[] into a string[] of csv strings where each csv is limited to a maximum of 4000 characters. The values in the array could be anything between 1 and int.MaxValue.</p> <p>Here is my final code:</p> <pre><code>public static string[] GetCSVsFromArray(int[] array, int csvLimit) { List&lt;string&gt; parts = new List&lt;string&gt;(); StringBuilder sb = new StringBuilder(); foreach(int id in array) { string intId = id.ToString(); if (sb.Length + intId.Length &lt; csvLimit) sb.Append(intId).Append(","); else { if (sb.Length &gt; 0) sb.Length--; parts.Add(sb.ToString()); sb.Length = 0; } } if(sb.Length&gt;0) parts.Add(sb.ToString()); return parts.ToArray(); } </code></pre> <p>Is there a more efficient way to do this?</p> <p>So here is what I am now using (I was able to change the return parameter to the List type to save the ToArray() call at the end):</p> <pre><code>public static List&lt;string&gt; GetCSVsFromArray(int[] array, int csvLimit) { List&lt;string&gt; parts = new List&lt;string&gt;(); StringBuilder sb = new StringBuilder(); foreach(int id in array) { string intId = id.ToString(); if (sb.Length + intId.Length &lt; csvLimit) sb.Append(intId).Append(","); else { if (sb.Length &gt; 0) sb.Length--; parts.Add(sb.ToString()); sb.Length = 0; } } if(sb.Length&gt;0) parts.Add(sb.ToString()); return parts; } </code></pre> <p>Performance results:</p> <p>10,000,000 items csv Limit of 4000 characters</p> <ul> <li>Original: 2,887.488ms</li> <li>GetIntegerDigitCount: 3105.355ms</li> <li>Final: 2883.587ms</li> </ul> <p>Whilst I only saved 4ms removing the ToArray() call on my developer machine this seems to make a significant difference on a much slower machine (saved over 200ms on a DELL D620)</p>
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    1. USJohn Hunter
    1. USJohn Hunter
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      1. USMuath Ali
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      1. VTUpMod
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    1. COYou are doing redundant `parts.ToArray()` which doing memory copy for the all items under the hood
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      1. USsll
    2. COYou are throwing away the value of intId when you create a new line?
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      1. USHuusom
    3. COWhy do I get the impression that you are [rolling your own CSV parser](http://secretgeek.net/csv_trouble.asp)? Please don't do that. Don't write such code.
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      1. USDarin Dimitrov
 

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