IP Format check, IP-int Conversion

  Public   Static   Bool Checkipaddress ( String IP)
{
String Pattern =   @" (\ D {1, 2}) | (1 \ D {2}) | (2 [0-4] \ D) | (25 [0-5]) \.) {3} (\ D {1, 2}) | (1 \ D {2}) | (2 [0-4] \ D) | (25 [0-5]) " ;
System. Text. regularexpressions. RegEx =   New System. Text. regularexpressions. RegEx (pattern );
If (RegEx. Match (IP). Success)
{
Return   True ;
}
Else
{
Return   False ;
}
}

Private   Static   Long Iptoint ( String IP)
{
Char [] Separator =   New   Char [] { ' . ' };
If (IP. Split (separator). Length =   3 )
{
IP = IP +   " . 0 " ;
}
String [] Strarray = IP. Split (separator );
Long Num2 = (( Long . Parse (strarray [ 0 ]) *   0x100l ) *   0x100l ) *   0x100l ;
Long Num3 = ( Long . Parse (strarray [ 1 ]) *   0x100l ) *   0x100l ;
Long Num4 =   Long . Parse (strarray [ 2 ]) *   0x100l ;
Long Num5 =   Long . Parse (strarray [ 3 ]);
Return (Num2 + Num3) + Num4) + Num5 );
}

Private   Static   String Inttoip ( Long Ip_int)
{
Long Num = ( Long ) (Ip_int &   0xff000000l ) >   0x18 );
If (Num <   0l )
{
Num + =   0x100l ;
}
Long Num2 = (Ip_int &   0xff0000l ) >   0x10 ;
If (Num2 <   0l )
{
Num2 + =   0x100l ;
}
Long Num3 = (Ip_int &   0xff00l ) >   8 ;
If (Num3 <   0l )
{
Num3 + =   0x100l ;
}
Long Num4 = Ip_int &   0 xffl ;
If (Num4 <   0l )
{
Num4 + =   0x100l ;
}
Return (Num. tostring () +   " . "   + Num2.tostring () +   " . "   + Num3.tostring () +   " . "   + Num4.tostring ());
}