How to specify exponential constants in C#?

I've got some C code that defines a exponential number as a constant. How do I write this in C#?

开发者_开发技巧    double TOL = 1.E-8d;
    double TOL2 = 1.E - 8;

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If there are no numbers after the decimal, you don't include the point. Same as in C/C++/etc. So:

double TOL= 1E-8;
double TOL2 = 1E-8;

Or maybe, for a different value:

double TOL = 1.5E-8;

This is in the spec, section 2.4.4.3:

http://msdn.microsoft.com/en-us/library/ms228593.aspx

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    double tol = 1.0e8;
    double tol2 = 1.0e-8;

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You were very close with your first form - but you just needed a digit after the ".", or remove the "." entirely:

double TOL = 1.0E-8d;
double TOL = 1E-8d;

See section 2.4.4.3 of the C# language spec for the rules around this. Note that you can use a lower-case "e" if you want, too:

double TOL = 1.0e-8d;
double TOL = 1e-8d;

And double is the default type if you omit the suffix from a "real" literal, so these are valid too:

double TOL = 1.0e-8;
double TOL = 1e-8;

... but personally I'd include the suffix for readability.

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This is how you do it in C#:

double value = -4.42330604244772E-305;

See also MSDN on System.Double.

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This is slightly different example, and not for exponential numbers.

double value = 1744056d is reported as error by g++ on Linux.

double value = 1744056.0d is fine.