//determine whether the input value is a number
    public static bool IsNumeric(string someValue)
    {
        Regex isNumber = new Regex(@"^d+$");
        try
        {
            Match m = isNumber.Match(someValue);
            return m.Success;
        }
        catch (FormatException)
        {return false;}
    }

int x;
double y;
string spork = "-3.14";

if (int.TryParse(spork, out x))
    Console.WriteLine("Yay it's an int (boy)!");
if (double.TryParse(spork, out y))
    Console.WriteLine("Yay it's an double (girl)!");

Regex isNumber = new Regex(@"^[-+]?(d*.)?d+$");

// Determine whether the input value is a number
public static bool IsNumeric(string someValue)
{
  return new Regex(@"^[-+]?(d*.)?d+$").IsMatch(someValue);
}

^-?d+$

^-?d*.?d*$

^-?d*.?d*(ed+)?$

public static bool IsNumeric(this string value)
{
    double temp;
    return double.TryParse(value.ToString(), out temp);
}

string someValue = "89.9";
if (someValue.IsNumeric()) // will be true in the US, but not in Sweden
{
    // wow, it's a number!
]

public static bool IsNumeric(string value)
{
    bool isNumber = true;

    bool afterDecimal = false;
    for (int i=0; i<value.Length; i++)
    {
        char c = value[i];
        if (c == '-' && i == 0) continue;

        if (Char.IsDigit(c))
        {
            continue;
        }

        if (c == '.' && !afterDecimal)
        {
            afterDecimal = true;
            continue;
        }

        isNumber = false;
        break;
    }

    return isNumber;
}