string FilterfileName(string strName)

 {

    string result=string.Empty ;

    if (string.IsNullOrWhiteSpace(strName))

    {

       //do something

    }

    else

    {

     result = strName.Replace("\\", "_").Replace("/", "_").Replace(":", "_")

              .Replace("*","_").Replace("?","_").Replace("<","_")

              .Replace(">","_").Replace("|","_").Replace("\"","_");

    }

    return result;

 }