Replace NULL with nullptr in C++ sources (BioDynaMo#450)

Author: stanbot8

benchmark/main.cc

@@ -9,5 +9,5 @@ int main(int argc, char** argv) {
   ::benchmark::Initialize(&argc, argv);
   if (::benchmark::ReportUnrecognizedArguments(argc, argv))
     return 1;
-  ::benchmark::RunSpecifiedBenchmarks(NULL, rep);
+  ::benchmark::RunSpecifiedBenchmarks(nullptr, rep);
 }

src/core/param/command_line_options.cc

@@ -60,7 +60,7 @@ void CommandLineOptions::Parse() {
     argv_copy[i] = (char*)malloc(length);
     memcpy(argv_copy[i], argv_[i], length);
   }
-  argv_copy[argc_] = NULL;
+  argv_copy[argc_] = nullptr;
 
   // Perform parsing (consumes argc_copy and argv_copy)
   if (parser_) {

src/core/visualization/paraview/mapped_data_array.h

@@ -364,7 +364,7 @@ void MappedDataArray<TScalar, TClass, TDataMember>::Squeeze() {
 template <typename TScalar, typename TClass, typename TDataMember>
 vtkArrayIterator* MappedDataArray<TScalar, TClass, TDataMember>::NewIterator() {
   vtkErrorMacro(<< "Not implemented.");
-  return NULL;
+  return nullptr;
 }
 
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