C # hex conversion

// int turn hexadecimal (long same type) 
int A = 90 ;
 String STR Convert.ToString = (A, 16 ); // . 5A 

// int binary transfected 
int A = 90 ;
 String STR = Convert.ToString (A, 2 ); // 1011010 

// int transfer byte 
int A = 90 ;
 String STR = Convert.Tobyte (A); // 0x5A 

// 16 hexadecimal switch 10 
String hex = " . 5A " ;
 String AA = the Convert .ToInt32 (hex, 16) .ToString (); // 90 

// 16 transfer binary hexadecimal 
String hex = " . 5A " ;
 String AA = Convert.ToString (Convert.ToInt32 (hex, 16 ), 2 ); // 1011010
 // ten hex decimal string transfected   
     public  string ConvertHexToIntStr ( string hexstr) 
        { 
            IF (hexstr.StartsWith ( " 0x " )) 
            { 
                hexstr = hexstr.Substring ( 2 ); 
            } 

            //If it is not a valid string or a hexadecimal character string length is greater than 16 or is empty, both return NULL 
            IF (IsHexadecimal (hexstr) || hexstr.Length>! 16 || String .IsNullOrEmpty (hexstr)) 
            { 
                return  null ; 
            } 
            IF (hexstr.Length> . 8 ) 
            { 
                return Convert.ToInt64 (hexstr, 16 ) .ToString (); 
            } 
            the else  IF (hexstr.Length> . 4 ) 
            { 
                return Convert.ToInt32 (hexstr, 16 ) .ToString (); 
            } 
            the else 
            { 
                returnConvert.ToInt16 (hexstr, 16 ) .ToString (); 
            } 
        } 
        // determines whether the hexadecimal string 
        public  BOOL IsHexadecimal ( String STR) 
        { 
            const  String the PATTERN = @ " [A-Fa of the-f0-9] $ + " ;
             return System.Text.RegularExpressions.Regex.IsMatch (STR, the PATTERN); 
        }