Is there a meaningful difference between “Double” and “double” in .Net?

问题

As regards best practices, is there a meaningful difference between using:

Double d;

and

double d;

I know best practices are fraught with contradictions, so I know the answers may vary here. I just want to know the pragmatic difference between the two.

回答1:

There is no difference. double is just an alias for System.Double in C#.

Note that VB.NET doesn't have the same aliasing (int for System.Int32, double for System.Double, etc), so the aliasing is just applicable to C#, not .NET as a whole.

回答2:

No, there's no difference: double is a C# keyword that's an alias for the System.Double type.

回答3:

a bit difference here.

-You can have class,parameter,var named "Double" but if u want to name it "double" u must type @double.

-You can use Qualifier for Double but not for double. ex

System.Double d; //Correct
System.double d; //incorrect. Compiler error: Identifier expected for "System." .
Double Double,@double;//Correct
double double;//incorrect ,Identifier expected for both doubles

the same thing for classes and parameters....also the same for String-string,Boolean-bool .....

回答4:

In C# the Double and double are the same, however Double guranateed to be the same across all .NET platforms, and as far as I remember the double IS the same on all platform, but is not guaranteed as such (despite being it de facto).

回答5:

Actually... after disassemble I found out that System.Double is a wrapper around double... So double is not a "shortcut" to System.Double.

来源：https://stackoverflow.com/questions/3951224/is-there-a-meaningful-difference-between-double-and-double-in-net