Testing for -nan (in the debugger)

[John E]

We all know that when setting breakpoints we can specify a condition - for example it can be specified to stop only when a value is zero. Here's some code that's causing a problem for me:-

double
HighFrequencyAudioCurve::processDouble(const double *R__ mag, int increment)
{
    double result = 0.0;

    const int sz = m_lastPerceivedBin;

    for (int n = 0; n <= sz; ++n) {
        result = result + mag[n] * n; // <--- 'result' ends up as -nan
    }

    return result;
}

After going around the loop several hundred times, result ends up as -nan - but unfortunately, -nan isn't accepted as a condition for a breakpoint. VS gives me this dialog at runtime:-



Can anyone suggest some way to test for -nan ?

[John E]

It's okay - I solved it by calling isnan() and placing a breakpoint if the return value was non-zero.

BTW - does anyone know what the statement double *R__ mag means..? I've never come across R__ before

[Edit...] If it helps, I just found that R__ is a #define saying #define R__ __restrict