C# : Check value stored inside string object is decimal or not

Use the Decimal.TryParse function.

decimal value;
if(Decimal.TryParse(strOrderId, out value))
  // It's a decimal
else
  // No it's not.

You can use Decimal.TryParse to check if the value can be converted to a Decimal type. You could also use Double.TryParse instead if you assign the result to a variable of type Double.

MSDN example:

string value = "1,643.57";
decimal number;
if (Decimal.TryParse(value, out number))
   Console.WriteLine(number);
else
   Console.WriteLine("Unable to parse '{0}'.", value);

decimal decValue;

if (decimal.TryParse(strOrderID, out decValue)
{ / *this is a decimal */ }
else
{ /* not a decimal */}