use empty()

GUI/Model/Sample/SampleItem.cpp

@@ -128,7 +128,7 @@ bool SampleItem::layerIsAmbientOrSubstrate(const LayerItem* layer, bool check_am
     // ignore empty stacks
     for (int i = components.size() - 1; i >= 0; i--) {
         if (auto* stack = dynamic_cast<LayerStackItem*>(components[i]))
-            if (!stack->uniqueLayerItems().size() || (stack->numberOfPeriods() == 0))
+            if (stack->uniqueLayerItems().empty() || (stack->numberOfPeriods() == 0))
                 components.erase(components.begin() + i);
     }
     ASSERT(components.size());

Sample/Multilayer/Sample.cpp

@@ -224,7 +224,7 @@ std::string Sample::validateAmbientSubstrate() const
     auto outer_components = m_outer_stack->components();
     for (int i = outer_components.size() - 1; i >= 0; i--)
         if (const auto* stack = dynamic_cast<const LayerStack*>(outer_components[i]))
-            if (!stack->unwrapped().size())
+            if (stack->unwrapped().empty())
                 outer_components.erase(outer_components.begin() + i);
 
     std::vector<std::string> errs;