Binary String to Integer

Question

I have a binary string, entered by the user, which I need to convert to an integer.

At first, I naively used this simple line:

Convert.ToInt32("11011",2); 

Unfortunately, this throws an exception if the user enters the integer directly.

Convert.ToInt32("123",2); // throws Exception 

How can I make sure that the string entered by the user actually is a binary string?

• try..catch
• Int32.TryParse

Thanks

Answer 1

You could use a Regex to check that it is "^[01]+$" (or better, "^[01]{1,32}$"), and then use Convert?

of course, exceptions are unlikely to be a huge problem anyway! Inelegant? maybe. But they work.

Example (formatted for vertical space):

static readonly Regex binary = new Regex("^[01]{1,32}$", RegexOptions.Compiled); static void Main() {     Test("");     Test("01101");     Test("123");     Test("0110101101010110101010101010001010100011010100101010"); } static void Test(string s) {     if (binary.IsMatch(s)) {         Console.WriteLine(Convert.ToInt32(s, 2));     } else {         Console.WriteLine("invalid: " + s);     } } 

Answer 2

Thanks for the great and incredibly fast answer!

Unfortunately, my requirements changed. Now the user can pretty much enter any format. Binary, Decimal, Hex. So I decided try - catch just provides the simplest and cleanest solution.

So just for good measure I am posting the code I am using now. I think it is pretty clear and even somewhat elegant, or so I think^^.

switch (format) {     case VariableFormat.Binary:         try         {             result = Convert.ToInt64(value, 2)         }         catch         {             // error handling         }         break;     case VariableFormat.Decimal:         try         {             result = Convert.ToInt64(value, 10)         }         catch         {             // error handling         }         break;     case VariableFormat.Hexadecimal:         try         {             result = Convert.ToInt64(value, 16)         }         catch         {             // error handling         }         break; } 

So thanks for encouraging me to use try - catch, I think it really improved the readibility of my code.

Thanks