private clsZipCode getZipCodeInformationAtRecordNumber(string zipCodeToSearch)
{
string pathFileNameBinary = Path.Combine(Application.StartupPath,
"ZipCodes_1990Census_sortedAscending.bin");
const int recordLength = 109;
clsZipCode zipCode = new clsZipCode();
using (FileStream fs = new FileStream(pathFileNameBinary, FileMode.Open))
using (BinaryReader br = new BinaryReader(fs))
{
long numberOfRecords = br.BaseStream.Length / recordLength;
long start = 0;
long middle = numberOfRecords / 2;
long end = numberOfRecords;
bool found = false;
while (start <= end)
{
long recordPos = middle * recordLength;
br.BaseStream.Seek(recordPos, SeekOrigin.Begin);
zipCode.BinaryDeserialize(br);
if (String.Compare(zipCode.ZipCode, zipCodeToSearch) == 0)
{
found = true;
break;
}
else if (String.Compare(zipCode.ZipCode, zipCodeToSearch) < 0)
{
start = middle + 1;
middle = (end + start) / 2;
}
else
{
end = middle - 1;
middle = (start + end) / 2;
}
}
if (found == false)
{
showMessage("The Zip Code " + zipCodeToSearch + " was not found.");
return(null);
}
}
return(zipCode);
}
