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POMy C# ListView Compare Function is too slow
 

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  1. POMy C# ListView Compare Function is too slow
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    <p>I am trying to sort a <code>ListView</code> which also has a <code>DateTime</code> column. This is the code I use:</p> <pre><code>public bool isDate(Object obj) { string strDate = obj.ToString(); try { DateTime dt = DateTime.Parse(strDate); if (dt != DateTime.MinValue &amp;&amp; dt != DateTime.MaxValue) return true; return false; } catch { return false; } } public int Compare(object o1, object o2) { if (!(o1 is ListViewItem)) return (0); if (!(o2 is ListViewItem)) return (0); ListViewItem lvi1 = (ListViewItem)o2; string str1 = lvi1.SubItems[ByColumn].Text; ListViewItem lvi2 = (ListViewItem)o1; string str2 = lvi2.SubItems[ByColumn].Text; int result; if (lvi1.ListView.Sorting == SortOrder.Ascending) { if (isDate(str1) &amp;&amp; isDate(str2)) result = DateTime.Compare(DateTime.Parse(str1), DateTime.Parse(str2)); else result = String.Compare(str1, str2); } else result = String.Compare(str2, str1); LastSort = ByColumn; return result; } </code></pre> <p>The <code>ListView</code> holds about 2000 entries and the problem is that it's very slow. What am I doing wrong? Any ideas?</p> <p>Thanks in advance!</p> <p><strong>Edit:</strong> Thank you very much. I am new to this and here is my code now. It is much faster and I fixed my logic.</p> <pre><code>public int Compare(object o1, object o2) { var lvi1 = o2 as ListViewItem; var lvi2 = o1 as ListViewItem; if (lvi1 == null || lvi2 == null) return 0; string str1 = lvi1.SubItems[ByColumn].Text; string str2 = lvi2.SubItems[ByColumn].Text; int result; DateTime dateValue1 = new DateTime(); DateTime dateValue2 = new DateTime(); if (lvi1.ListView.Sorting == SortOrder.Ascending) { if (DateTime.TryParse(str1, out dateValue1) &amp;&amp; DateTime.TryParse(str2, out dateValue2)) result = DateTime.Compare(dateValue1, dateValue2); else result = String.Compare(str1, str2); } else { if (DateTime.TryParse(str1, out dateValue1) &amp;&amp; DateTime.TryParse(str2, out dateValue2)) result = DateTime.Compare(dateValue2, dateValue1); else result = String.Compare(str2, str1); } LastSort = ByColumn; return result; } </code></pre>
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    1. USMaciej D.
    1. USpelz
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    1. COIs this using WPF? If so, could you tag it as such?
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      1. USmindandmedia
    2. COWhy aren't you using `DateTime.TryParse()` instead of catching a parsing exception? It returns a `bool` and uses an output parameter to set the value if it succeeds.
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      1. USBryan Crosby
    3. COAlso I think there is something wrong with your logic, when sort order is ascending you care about DateTime fields, but in other case (descending) you aren't care about this.
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      1. USSaeed Amiri
 

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