Complex sort order using entity framework - regex

Question

Please help how can I sort this kind of list. Any help would be appreciated.
I have a list of string
List<string> lst = new List<string>();
lst.Add("2.1");
lst.Add("2.10A");
lst.Add("2.1B");
lst.Add("2.2");
lst.Add("ABC");
lst.Add("ABC1");
lst.Add("1.0");
sort order would be:
decimal numbers will treat like a whole number if the string starts with decimal.
number first followed by letters
Sample result:
1.0, 2.1, 2.1B, 2.2, 2.10A, ABC, ABC1
P.S. If possible i can order it using Oracle and entity framework will be a better solution.

Answer 1

How about this? Use the sort() method on the list passing in a comparison function. Then in the comparison function use the regex to extract the initial decimal values removing '.' for comparison. When comparing a number with a string, number is less. Compare number first, if equal, then compare the remaining string component.
Explanation of regexMatchDecimal:
?: non-capturing group.
\d+ match one or more digits.
[.] match a literal .
The regex in GetString will just extract the remaining string component after the decimal if there is one and put the result in the first group ().
[...] Removed original code as it is no longer relevant.
Update
As per the comment, first the integer part and then the integer and fractional part as a whole number will be compared.
The new version:
static public class Program
{
static string regexMatchDecimal = #"(?:^\d+$)|^(?:\d+[.]\d+)";
static string GetString( string input )
{
string result = "";
Match match = Regex.Match( input, regexMatchDecimal + #"(.+)" );
if( match.Success && match.Groups.Count > 1 )
{
result = match.Groups[1].Value;
}
return result;
}
static bool GetIntValue(string input, out int result)
{
result = 0;
bool isConverted = false;
Match match = Regex.Match( input, regexMatchDecimal );
if( match.Success )
{
int pos = match.Value.IndexOf( '.' );
string resultStr = "";
if( pos != -1 )
{
resultStr = match.Value.Substring( 0, pos );
}
else
{
resultStr = match.Value;
}
isConverted = int.TryParse( resultStr, out result );
}
return isConverted;
}
static bool GetDecimalWholeValue( string input, out int result )
{
result = 0;
bool isConverted = false;
Match match = Regex.Match( input, regexMatchDecimal );
if( match.Success )
{
string resultStr = match.Value.Replace( ".", "" );
isConverted = int.TryParse( resultStr, out result );
}
return isConverted;
}
static public int Compare( string x, string y )
{
int xRes = 0;
int yRes = 0;
bool hasXNumber = GetIntValue( x, out xRes );
bool hasYNumber = GetIntValue( y, out yRes );
int result = 0;
if( hasXNumber && hasYNumber )
{
result = xRes.CompareTo( yRes );
if( result == 0 )//if same compare whole number decimal components
{
hasXNumber = GetDecimalWholeValue( x, out xRes );
hasYNumber = GetDecimalWholeValue( y, out yRes );
result = xRes.CompareTo( yRes );
if( result == 0 ) //compare as string
{
string xSubStr = GetString( x );
string ySubStr = GetString( y );
result = xSubStr.CompareTo( ySubStr );
}
}
}
else if( hasXNumber && !hasYNumber )
{
result = - 1;
}
else if( !hasXNumber && hasYNumber )
{
result = 1;
}
else
{
result = x.CompareTo( y );
}
return result;
}
static void Go(List<string> lst)
{
lst.Add( "2.1" );
lst.Add( "2.10A" );
lst.Add( "2.1B" );
lst.Add( "D.3" );
lst.Add( "2.2" );
lst.Add( "2.1A" );
lst.Add( "ABC" );
lst.Add( "2" );
lst.Add( "ABC1" );
lst.Add( "0.399C" );
lst.Add( "1.0" );
lst.Add( "3" );
lst.Sort( Compare );
foreach( var val in lst )
{
Console.WriteLine(val);
}
}
static void Main( string[] args )
{
List<string> lst = new List<string>();
Go(lst);
}
}
Output is now:
0.399C
1.0
2
2.1
2.1A
2.1B
2.2
2.10A
3
ABC
ABC1
D.3