Difference in Double & double

Question

I am confuse in term of lower-case double and upper-case Double.
what is the difference between double/Double... ?

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace test
{
     static void Main(string[] args)
        {
            Double a = 100;
            double b = 200;

            Console.Write("{0},{1}",a,b);
        }

    }
}

Both do same work,so why looking different i.e, Double and double...?

[Relevant docs](https://msdn.microsoft.com/en-us/library/ya5y69ds.aspx). — James Thorpe, Dec 02 '15 at 10:46
Other way round because double is C# language while System.Double is the structure — Sascha, Dec 02 '15 at 10:46
you mean either i use double or Double. They always do same work...? — Muhammed Naqi, Dec 02 '15 at 10:46
@MuhammedNaqi Yes, they are equivalent. However, it is a good practice to use `double` as type, and `Double` if you refer to its static members. — Yeldar Kurmangaliyev, Dec 02 '15 at 10:47
AFAIK, `(Double)-1` will not compile, while `(double)-1` will. — user4003407, Dec 02 '15 at 10:48
@PetSerAl, that's wrong. You can using `system.double` like `(System.Double)(-1);` — Rahul, Dec 02 '15 at 10:51
@Rahul But you can not using it like `(System.Double)-1` because it interpreted as subtraction while `(double)-1` interpreted as cast. — user4003407, Dec 02 '15 at 10:52

Sascha · Accepted Answer · 2015-12-02T10:47:23.917

1

Double is System.Double while double is the C# double data type. They are the same, that means the C# double type maps to System.Double

Relevant documentation:

https://msdn.microsoft.com/en-us/library/system.double(v=vs.110).aspx

https://msdn.microsoft.com/en-us/library/678hzkk9.aspx

edited Dec 02 '15 at 10:47

answered Dec 02 '15 at 10:45

Sascha

9,732
3
38
61

1

It's C# and not C##. BTW, double is just an alias for system.double – Rahul Dec 02 '15 at 10:46

score 0 · Answer 2 · answered Dec 02 '15 at 10:47

0

These are reserved 'keywords' and just maps to the other type (double maps to Double) like said, it is an alias

answered Dec 02 '15 at 10:47

Sloth

172
8

Difference in Double & double

2 Answers2