Question

Hi im trying to do a string match for some certain things in my webservice however I get stuck at comparing a double

public List<Customers> GetCustomer(string anything)
{
    List<Customers> customers = customermembers.Where(n =>
    string.Equals(n.CustomerID, anything, StringComparison.CurrentCultureIgnoreCase)
    || string.Equals(n.FirstName, anything, StringComparison.CurrentCultureIgnoreCase)
    || string.Equals(n.LastName, anything, StringComparison.CurrentCultureIgnoreCase)
    || double.Equals(n.Age, anything, StringComparison.CurrentCultureIgnoreCase) //this like
    ).ToList();
    return customers;
}

How do you compare a double?

My DataContract looks like this:

[DataMember(Name = "Age")]
public double Age { get; set; }

Answer 1

How do you compare a double?

I assume that you want to compare two double values representing age and that anything is indeed not a string but a double (it is a bit hard to tell from the question because the way anything is used doesn’t make much sense).

Best thing you can do is to switch the type of Age from double to decimal (or even better int if the age is an integer). Doing that avoid rounding errors.

However, if you want to stick to floating point numbers you can simply compare two double values using ==:

a == b

or use the static object.Equals method:

Equals(a, b)

If you perform calculations on the ages you will probably get rounding problems and then you will have to use a small epsilon value that represents the rounding precision you want to use:

const double Epsilon = 0.0000000001;
var areEqual = Math.Abs(a - b) < Epsilon;