Prefer empty to size of zero

[goatbar]

double
ElevationMatrixCell::getAvg() const
{
        return  zvals.size() ?
                ztot / static_cast<double>(zvals.size()) :
                DoubleNotANumber;
}

Should become:

double
ElevationMatrixCell::getAvg() const
{
    return !zvals.empty() ? ztot / static_cast<double>(zvals.size())
                        : DoubleNotANumber;
}

or better yet, drop the not (!) in the test.

double
ElevationMatrixCell::getAvg() const
{
    return zvals.empty()
        ? DoubleNotANumber
        : ztot / static_cast<double>(zvals.size()) ;
}

[goatbar]

And there are some easy to find instances of the same thing:

find . -name \*.cpp | xargs egrep '[.]size()' | egrep '== *0|0 *=='
./geomgraph/EdgeEndStar.cpp:	if (edgeMap.size()==0) return nullCoord;
./geomgraph/EdgeEndStar.cpp:	if (edgeMap.size()==0) return true;
./operation/buffer/SubgraphDepthLocater.cpp:	if (stabbedSegments.size()==0) return 0;
./operation/overlay/LineBuilder.cpp:	if ( v3d.size() == 0 )
./linearref/ExtractLineByLocation.cpp:	if (newCoordinateArray.size() == 0)

[Daniel Baston <dbaston@…>]

In c4bfa45/git:

Use empty() instead of size() where possible

Fixes #860