Function ConvertStringToFloat

IO/PostgreSQL/vtkPostgreSQLQuery.cxx:788–865

//------------------------------------------------------------------------------

vtkVariant ConvertStringToFloat(bool isBinary, const char* rawData)
{
  if (isBinary)
  {
    // As of PostgreSQL version 8.3.0, libpq transmits a float in network
    // byte order -- that is, it reinterprets the bits as an unsigned int
    // and then transmits them that way.  This... frightens me.  It assumes
    // that both sender and recipient use IEEE floats.  Still, I'm not sure
    // there's any other good way to do it.
    unsigned int intResult;
    ConvertFromNetworkOrder(intResult, rawData);

    // This is the idiom that libpq uses internally to convert between the
    // two types.
    union
    {
      unsigned int i;
      float f;
    } swap;
    swap.i = intResult;
    float floatResult = swap.f;

    return vtkVariant(floatResult);
  }
  else
  {
    std::string rawString(rawData);
    float finalResult;

    // Catch NaN
    if (rawData[0] == 'N' || rawData[0] == 'n')
    {
      if (std::numeric_limits<float>::has_quiet_NaN)
      {
        finalResult = std::numeric_limits<float>::quiet_NaN();
      }
      else
      {
        // C99 defines a NAN macro.  If it's there, that solves our problem.
#if defined(NAN)
        finalResult = NAN;
#else
        float zero = 0.0;
        finalResult = zero / zero;
#endif
      }
    }
    else if (rawString == "Infinity")
    {
      if (std::numeric_limits<float>::has_infinity)
      {
        finalResult = std::numeric_limits<float>::infinity();
      }
      else
      {
        finalResult = VTK_FLOAT_MAX;
      }
    }