Are Double constants truncated for display in VS?

问题

The constant Math.Pi is, according to reflector and MSDN, equal to 3.14159265358979323846. When looking at the Math class in Visual Studio 2010, the value is displayed as 3.14159. Whom can I blame for truncating precious constants?

回答1:

I don't know why the OP isn't posting this, as it would clear things up so incredibly much, but you can reproduce as follows:

Open the IDE
Enter Math.PI into a .cs file.
Right-click on Math.PI and click on 'Go To Definition'

This opens up the Metadata file for Math, which contains the following:

    //
    // Summary:
    //     Represents the ratio of the circumference of a circle to its diameter, specified
    //     by the constant, π.
    public const double PI = 3.14159;

回答2:

Sorry to repeat myself, but how do you get that number? If I hover over the constant or print it in the Immediate or Watch window in VS2010, I get 3.1415926535897931, which is also the value I get when looking at mscorlib in Reflector.

While it is less precision than MSDN claims, it is still far better than the number you're talking about. VS has to pick a formatting for printing floating point numbers. With the results I see I find the default quite acceptable.

回答3:

You can blame the VS metadata view, which is what you get when you press F12 on something you don't have the source to.

At least I presume that's what you're doing, because it's the only place I can find the truncated constant you're talking about.

Why does it do it / where does it get that value from? Who knows...

回答4:

Maybe you have a plugin for VS 2010 that is changing the output of the number. Or maybe you're displaying the number in a display context that has to truncate the number to fit. Where exactly in Visual Studio are you viewing this number?

来源：https://stackoverflow.com/questions/3742753/are-double-constants-truncated-for-display-in-vs

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