Question

Im trying to create a method that checks a string against a regular express and returns a register type(mips). The problem is that I can’t seem to be able to create the correct regex.
Please take a look and make suggestions. Thanks

 public static RegisterType CheckRegex(this string source)
        {
            var tempMatch = new Regex("$t0|$t1|$t2|$t3|$t4|$t5|$t6|$t7|$t8|$t9|").Match(source);  //$t0 - $t9
            if(tempMatch.Length == source.Length)
                return RegisterType.Temporary;
            var storeMatch = new Regex(@"(^\$s)+[0-9]").Match(source);  //$s0 - $s9
            if (storeMatch.Length == source.Length)
                return RegisterType.Store;
            var reservedMatch = new Regex(@"").Match(source);            //$k0 - $k1
            if (reservedMatch.Length == source.Length)
                return RegisterType.OSReserved;
            var constantMatch = new Regex(@"0-9").Match(source);        //Any integer
            if (constantMatch.Length == source.Length)
                return RegisterType.Constant;
            var memoryMatch = new Regex("").Match(source);
            if (memoryMatch.Length == source.Length)
                return RegisterType.Memory;

            return RegisterType.Invalid;
        }

UPDATE: Everything is working now ,excluding my Memory Regex

public static RegisterType GetRegisterType(this string source)
        {
            if (Regex.IsMatch(source, @"\$t[0-9]"))
                return RegisterType.Temporary; // $t0 - $t9
            if (Regex.IsMatch(source, @"\$s[0-9]"))
                return RegisterType.Store; // $s0 - $s9
            if (Regex.IsMatch(source, @"\$k[0-1]"))
                return RegisterType.OSReserved; // $k0 - $k1
            if (Regex.IsMatch(source, @"[-+]?\b\d+\b"))
                return RegisterType.Constant;
            if (Regex.IsMatch(source, @"\$zero"))
                return RegisterType.Special;
            if (Regex.IsMatch(source, @"[a-zA-Z0-9]+\b\:"))
                return RegisterType.Label;
            if (Regex.IsMatch(source, @"\d+\b\(\$[s-t]\b[0-9])"))
                return RegisterType.Memory;
            return RegisterType.Invalid;

        }

Answer 1

As others have said, you need to escape the dollar signs in "$t0|$t1|$t2|$t3|$t4|$t5|$t6|$t7|$t8|$t9|" by prefixing them with a backslash. Also, you can write that more concisely as @"\$t[0-9]". That will match a dollar sign followed by 't' followed by a single digit. You’ve got a trailing pipe character followed by nothing, as well, that can be removed.