QCustomPlot Discussion and Comments

below is the source code of this funciton in version 2.1.1:

void QCPColorMapData::fill(double z)
{
  const int dataCount = mValueSize*mKeySize;
  memset(mData, z, dataCount*sizeof(*mData));
  mDataBounds = QCPRange(z, z);
  mDataModified = true;
}

Pay attention to the line of memset. The type of z and mData is double.
So there is no need for me to explain more.

This function may revert to version 2.1.0, which use for to fill data:

void QCPColorMapData::fill(double z)
{
  const int dataCount = mValueSize*mKeySize;
  for (int i=0; i<dataCount; ++i)
    mData[i] = z;
  mDataBounds = QCPRange(z, z);
  mDataModified = true;
}