ISO-8859-1 to UTF8 in ASP.NET 2
- by Gordon Carpenter-Thompson
We've got a page which posts data to our ASP.NET app in ISO-8859-1
<head>
    <META HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=iso-8859-1">
    <title>`Sample Search Invoker`</title>
</head>
<body>
<form name="advancedform" method="post" action="SearchResults.aspx">
    <input class="field" name="SearchTextBox" type="text" />
    <input class="button" name="search" type="submit" value="Search >" />
</form>
and in the code behind (SearchResults.aspx.cs)
System.Collections.Specialized.NameValueCollection postedValues = Request.Form;
String nextKey;
for (int i = 0; i < postedValues.AllKeys.Length; i++)
{
    nextKey = postedValues.AllKeys[i];
    if (nextKey.Substring(0, 2) != "__")
    {
        // Get basic search text
        if (nextKey.EndsWith(XAEConstants.CONTROL_SearchTextBox))
        {
            // Get search text value
            String sSentSearchText = postedValues[i];
            System.Text.Encoding iso88591 = System.Text.Encoding.GetEncoding("iso-8859-1");
            System.Text.Encoding utf8 = System.Text.Encoding.UTF8;
            byte[] abInput = iso88591.GetBytes(sSentSearchText);
            sSentSearchText = utf8.GetString(System.Text.Encoding.Convert(iso88591, utf8, abInput));
            this.SearchText = sSentSearchText.Replace('<', ' ').Replace('>',' ');
            this.PreviousSearchText.Value = this.SearchText;
        }
    }
}
When we pass through Merkblätter it gets pulled out of postedValues[i] as Merkbl?tter 
The raw string string is Merkbl%ufffdtter
Any ideas?