[Ed.: This is an old post but we feel it has valuable information about constexpr.]

This is a good article about constant expressions and computations at compile time. It gives good coverage of the new constexpr keyword for allowing compile-time and run-time evalution. constexpr is discussed rigorously with information on the rules required by the facility.

Compile-Time Computations

by Andrzej Krzemieński

[...] But now, consider the following example:

const int i = 2;

const char array[ i == 2 ? 64 : throw exception() ];

Throwing an exception (which is an expression) cannot be evaluated at compile-time, but since i == 2 is true, the third argument of conditional operator should not be evaluated; at least at run-time. So is the above a valid code? Not in C++03. It is valid however in C++11. Does this sound incredible? [...]

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