How to replace the keyword "nan" to check the contract assert?

[Ali Çehreli via Digitalmars-d-learn]

On 03/20/2015 09:24 PM, Dennis Ritchie wrote:> Hi,
 > How do I replace double.init?
 >
 > import std.stdio : writeln;
 > import std.algorithm : uninitializedFill;
 >
 > void main() {
 >
 >      double[] arr = new double[6];
 >      uninitializedFill(arr[0 .. $ - 2], 3.25);
 >      writeln(arr);
 >      assert(arr == [3.25, 3.25, 3.25, 3.25, double.init, double.init]);
 > /* not work */
 > }

nan cannot be used in comparisons. It is neither greater than nor less 
than any value. You cannot even compare it against itself. nan==nan 
would always be false.

The solution is to call std.math.isNaN. In this case, you have to split 
the assert into two. You can achieve the same thing in may ways but the 
following works:

     assert(arr[0 .. $ - 2] == [3.25, 3.25, 3.25, 3.25]);

     import std.algorithm;
     import std.math;
     assert(arr[$ - 2 .. $].all!isNaN);

Ali