Simplify checking of container (List/HashTable, strings) sizes

- can use 'XX.empty()' instead of 'XX.size() == 0', 'XX.size() < 1' or
  'XX.size() <= 0' or for simpler coding.
  It also has the same number of characters as '!XX.size()' and /might/ be
  more readable

- many size checking had 'XX.size() > 0', 'XX.size() != 0', or 'XX.size() >= 1'
  when a simple 'XX.size()' suffices

src/conversion/meshTables/boundaryRegion.C

@@ -114,7 +114,7 @@ Foam::Map<Foam::word> Foam::boundaryRegion::names
         {
             lookup.insert(iter.key(), lookupName);
         }
-    }    
+    }
 
     return lookup;
 }
@@ -139,7 +139,7 @@ Foam::Map<Foam::word> Foam::boundaryRegion::boundaryTypes() const
 
 Foam::label Foam::boundaryRegion::findIndex(const word& name) const
 {
-    if (!name.size())
+    if (name.empty())
     {
         return -1;
     }
@@ -254,7 +254,7 @@ void Foam::boundaryRegion::operator=(const Map<dictionary>& rhs)
 
 void Foam::boundaryRegion::rename(const dictionary& mapDict)
 {
-    if (!mapDict.size())
+    if (mapDict.empty())
     {
         return;
     }

src/conversion/meshTables/cellTable.C

@@ -208,7 +208,7 @@ Foam::word Foam::cellTable::name(const label& id) const
 
 Foam::label Foam::cellTable::findIndex(const word& name) const
 {
-    if (!name.size())
+    if (name.empty())
     {
         return -1;
     }
@@ -466,7 +466,7 @@ void Foam::cellTable::addCellZones
     forAll(zoneCells, zoneI)
     {
         zoneCells[zoneI].shrink();
-        if (zoneCells[zoneI].size() > 0)
+        if (zoneCells[zoneI].size())
         {
             zoneUsed[nZone++] = zoneI;
         }
@@ -509,7 +509,7 @@ void Foam::cellTable::addCellZones
 
 void Foam::cellTable::combine(const dictionary& mapDict, labelList& tableIds)
 {
-    if (!mapDict.size())
+    if (mapDict.empty())
     {
         return;
     }

src/conversion/meshWriter/starcd/STARCDMeshWriter.C

@@ -92,7 +92,7 @@ void Foam::meshWriters::STARCD::getCellTable()
         {
             cellTableId_.transfer(ioList);
 
-            if (!cellTable_.size())
+            if (cellTable_.empty())
             {
                 Info<< "no cellTable information available" << endl;
             }
@@ -116,7 +116,7 @@ void Foam::meshWriters::STARCD::getCellTable()
 
     if (useCellZones)
     {
-        if (!cellTable_.size())
+        if (cellTable_.empty())
         {
             Info<< "created cellTable from cellZones" << endl;
             cellTable_ = mesh_;
@@ -500,7 +500,7 @@ bool Foam::meshWriters::STARCD::write(const fileName& meshName) const
 {
     fileName baseName(meshName);
 
-    if (!baseName.size())
+    if (baseName.empty())
     {
         baseName = meshWriter::defaultMeshName;
 
@@ -535,7 +535,7 @@ bool Foam::meshWriters::STARCD::writeSurface
 {
     fileName baseName(meshName);
 
-    if (!baseName.size())
+    if (baseName.empty())
     {
         baseName = meshWriter::defaultSurfaceName;
 

src/conversion/polyDualMesh/polyDualMesh.C

@@ -758,7 +758,7 @@ void Foam::polyDualMesh::calcDual
 
         allBoundary.checkPointManifold(true, &nonManifoldPoints);
 
-        if (nonManifoldPoints.size() > 0)
+        if (nonManifoldPoints.size())
         {
             nonManifoldPoints.write();
 
@@ -1151,7 +1151,7 @@ void Foam::polyDualMesh::calcDual
         dynDualOwner.shrink();
         dynDualNeighbour.shrink();
         dynDualRegion.shrink();
-    
+
         OFstream str("dualInternalFaces.obj");
         Pout<< "polyDualMesh::calcDual : dumping internal faces to "
             << str.name() << endl;
@@ -1163,7 +1163,7 @@ void Foam::polyDualMesh::calcDual
         forAll(dynDualFaces, dualFaceI)
         {
             const face& f = dynDualFaces[dualFaceI];
-    
+
             str<< 'f';
             forAll(f, fp)
             {
@@ -1229,7 +1229,7 @@ void Foam::polyDualMesh::calcDual
         forAll(dualFaces, dualFaceI)
         {
             const face& f = dualFaces[dualFaceI];
-    
+
             str<< 'f';
             forAll(f, fp)
             {