diff --git a/CMakeLists.txt b/CMakeLists.txt
index 6202498..b4a28a1 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -7,6 +7,17 @@
 #Minimum required CMake Version
 cmake_minimum_required(VERSION 2.8.12)
 
+# Only set the cxx_standard if it is not set by someone else
+if (NOT DEFINED CMAKE_CXX_STANDARD)
+  set(CMAKE_CXX_STANDARD 14)
+endif()
+
+# strongly encouraged to enable this globally to avoid conflicts between
+# -Wpedantic being enabled and -std=c++20 and -std=gnu++20 for example
+# when compiling with PCH enabled
+set(CMAKE_CXX_EXTENSIONS OFF)
+
+
 #Project Name
 PROJECT(NCXX C CXX)
 set(PACKAGE "netcdf-cxx4" CACHE STRING "")
diff --git a/cxx4/ncAtt.cpp b/cxx4/ncAtt.cpp
index c373e73..9b639e4 100644
--- a/cxx4/ncAtt.cpp
+++ b/cxx4/ncAtt.cpp
@@ -65,22 +65,19 @@ NcType  NcAtt::getType() const{
   // get the identifier for the netCDF type of this attribute.
   nc_type xtypep;
   ncCheck(nc_inq_atttype(groupId,varId,myName.c_str(),&xtypep),__FILE__,__LINE__);
-  if(xtypep <= 12)
+  if (xtypep <= 12) {
     // This is an atomic type
     return NcType(xtypep);
-  else
-    // this is a user-defined type
-    {
-      // now get the set of NcType objects in this file.
-      multimap<string,NcType> typeMap(getParentGroup().getTypes(NcGroup::ParentsAndCurrent));
-      multimap<string,NcType>::iterator iter;
-      // identify the Nctype object with the same id as this attribute.
-      for (iter=typeMap.begin(); iter!= typeMap.end();iter++) {
-	if(iter->second.getId() == xtypep) return iter->second;
-      }
-      // return a null object, as no type was identified.
-      return NcType();
-    }
+  }
+  // this is a user-defined type
+  // now get the set of NcType objects in this file.
+  multimap<string,NcType> typeMap(getParentGroup().getTypes(NcGroup::ParentsAndCurrent));
+  // identify the Nctype object with the same id as this attribute.
+  for (const auto& type: typeMap) {
+    if(type.second.getId() == xtypep) return type.second;
+  }
+  // return a null object, as no type was identified.
+  return NcType();
 }
 
 // Gets attribute length.
diff --git a/cxx4/ncDim.cpp b/cxx4/ncDim.cpp
index c207b37..5b7ff9b 100644
--- a/cxx4/ncDim.cpp
+++ b/cxx4/ncDim.cpp
@@ -93,9 +93,8 @@ bool NcDim::isUnlimited() const
 	  // get all the unlimited dimension ids in this group
 	  vector<int> unlimdimid(static_cast<std::size_t>(numlimdims));
 	  ncCheck(nc_inq_unlimdims(groupId,&numlimdims,&unlimdimid[0]),__FILE__,__LINE__);
-	  vector<int>::iterator it;
 	  // now look to see if this dimension is unlimited
-	  it = find(unlimdimid.begin(),unlimdimid.end(),myId);
+	  const auto it = find(unlimdimid.begin(),unlimdimid.end(),myId);
 	  return it != unlimdimid.end();
   }
   return false;
diff --git a/cxx4/ncGroup.cpp b/cxx4/ncGroup.cpp
index aa543f1..60a7c9a 100644
--- a/cxx4/ncGroup.cpp
+++ b/cxx4/ncGroup.cpp
@@ -19,6 +19,8 @@
 #include "ncString.h"
 #include <cstddef>
 #include <ncException.h>
+#include <tuple>
+#include <utility>
 #include "ncCheck.h"
 using namespace std;
 using namespace netCDF::exceptions;
@@ -188,7 +190,7 @@ multimap<std::string,NcGroup> NcGroup::getGroups(NcGroup::GroupLocation location
 
   // record this group
   if(location == ParentsAndCurrentGrps || location == AllGrps) {
-    ncGroups.insert(pair<const string,NcGroup>(getName(),*this));
+    ncGroups.emplace(getName(), *this);
   }
 
   // the child groups of the current group
@@ -200,9 +202,9 @@ multimap<std::string,NcGroup> NcGroup::getGroups(NcGroup::GroupLocation location
       int* numgrps=NULL;
       // now get the id of each NcGroup and populate the ncGroups container.
       ncCheck(nc_inq_grps(myId, numgrps,&ncids[0]),__FILE__,__LINE__);
-      for(std::size_t i=0; i<groupCount;i++){
-        NcGroup tmpGroup(ncids[i]);
-        ncGroups.insert(pair<const string,NcGroup>(tmpGroup.getName(),tmpGroup));
+      for (auto ncid : ncids) {
+        NcGroup tmpGroup(ncid);
+        ncGroups.emplace(tmpGroup.getName(), tmpGroup);
       }
     }
   }
@@ -214,7 +216,7 @@ multimap<std::string,NcGroup> NcGroup::getGroups(NcGroup::GroupLocation location
       while(1) {
 	const NcGroup parentGroup(tmpGroup.getParentGroup());
 	if(parentGroup.isNull()) break;
-	ncGroups.insert(pair<const string,NcGroup>(parentGroup.getName(),parentGroup));
+	ncGroups.emplace(parentGroup.getName(), parentGroup);
 	tmpGroup=parentGroup;
       }
     }
@@ -222,11 +224,10 @@ multimap<std::string,NcGroup> NcGroup::getGroups(NcGroup::GroupLocation location
 
   // search in child groups of the children
   if(location == ChildrenOfChildrenGrps || location == AllChildrenGrps || location == AllGrps ) {
-    multimap<string,NcGroup>::iterator it;
     multimap<string,NcGroup> groups(getGroups(ChildrenGrps));
-    for (it=groups.begin();it!=groups.end();it++) {
-      multimap<string,NcGroup> childGroups(it->second.getGroups(AllChildrenGrps));
-      ncGroups.insert(childGroups.begin(),childGroups.end());
+    for (const auto& group : groups) {
+      multimap<string,NcGroup> childGroups(group.second.getGroups(AllChildrenGrps));
+      ncGroups.insert(childGroups.begin(), childGroups.end());
     }
   }
 
@@ -236,13 +237,12 @@ multimap<std::string,NcGroup> NcGroup::getGroups(NcGroup::GroupLocation location
 // Get the named child NcGroup object.
 NcGroup NcGroup::getGroup(const string& name,NcGroup::GroupLocation location) const{
   if(isNull()) throw NcNullGrp("Attempt to invoke NcGroup::getGroup on a Null group",__FILE__,__LINE__);
-  multimap<string,NcGroup> ncGroups(getGroups(location));
-  pair<multimap<string,NcGroup>::iterator,multimap<string,NcGroup>::iterator> ret;
-  ret = ncGroups.equal_range(name);
-  if(ret.first == ret.second)
+
+  const auto ret = getGroups(location).equal_range(name);
+  if (ret.first == ret.second) {
     return NcGroup();  // null group is returned
-  else
-    return ret.first->second;
+  }
+  return ret.first->second;
 }
 
 
@@ -251,12 +251,10 @@ NcGroup NcGroup::getGroup(const string& name,NcGroup::GroupLocation location) co
 set<NcGroup> NcGroup::getGroups(const std::string& name,NcGroup::GroupLocation location) const {
   if(isNull()) throw NcNullGrp("Attempt to invoke NcGroup::getGroups on a Null group",__FILE__,__LINE__);
   // get the set of ncGroups in this group and above.
-  multimap<std::string,NcGroup> ncGroups(getGroups(location));
-  pair<multimap<string,NcGroup>::iterator,multimap<string,NcGroup>::iterator> ret;
-  multimap<string,NcGroup>::iterator it;
-  ret = ncGroups.equal_range(name);
+  const auto ncGroups(getGroups(location));
+  const auto ret = ncGroups.equal_range(name);
   set<NcGroup> tmpGroup;
-  for (it=ret.first; it!=ret.second; ++it) {
+  for (auto it=ret.first; it!=ret.second; ++it) {
     tmpGroup.insert(it->second);
   }
   return tmpGroup;
@@ -301,10 +299,8 @@ int NcGroup::getVarCount(NcGroup::Location location) const {
 
   // search recursively in all child groups
   if(location == ChildrenAndCurrent || location == Children || location == All) {
-    multimap<string,NcGroup>::iterator it;
-    multimap<string,NcGroup> groups(getGroups());
-    for (it=groups.begin();it!=groups.end();it++) {
-      nvars += it->second.getVarCount(ChildrenAndCurrent);
+    for (auto group : getGroups()) {
+      nvars += group.second.getVarCount(ChildrenAndCurrent);
     }
   }
   return nvars;
@@ -326,9 +322,9 @@ multimap<std::string,NcVar> NcGroup::getVars(NcGroup::Location location) const {
       int* nvars=NULL;
       vector<int> varids(varCount);
       ncCheck(nc_inq_varids(myId, nvars,&varids[0]),__FILE__,__LINE__);
-      for(std::size_t i=0; i<varCount;i++){
-        NcVar tmpVar(*this,varids[i]);
-        ncVars.insert(pair<const string,NcVar>(tmpVar.getName(),tmpVar));
+      for (auto varid : varids) {
+        NcVar tmpVar(*this, varid);
+        ncVars.emplace(tmpVar.getName(), tmpVar);
       }
     }
   }
@@ -345,9 +341,9 @@ multimap<std::string,NcVar> NcGroup::getVars(NcGroup::Location location) const {
         int* nvars=NULL;
         vector<int> varids(varCount);
         ncCheck(nc_inq_varids(tmpGroup.getId(), nvars,&varids[0]),__FILE__,__LINE__);
-        for(std::size_t i=0; i<varCount;i++){
-          NcVar tmpVar(tmpGroup,varids[i]);
-          ncVars.insert(pair<const string,NcVar>(tmpVar.getName(),tmpVar));
+        for (auto varid : varids) {
+          NcVar tmpVar(tmpGroup, varid);
+          ncVars.emplace(tmpVar.getName(), tmpVar);
         }
       }
       // continue loop with the parent.
@@ -357,10 +353,8 @@ multimap<std::string,NcVar> NcGroup::getVars(NcGroup::Location location) const {
 
   // search recusively in all child groups.
   if(location == ChildrenAndCurrent || location == Children  || location == All ) {
-    multimap<string,NcGroup>::iterator it;
-    multimap<string,NcGroup> groups(getGroups());
-    for (it=groups.begin();it!=groups.end();it++) {
-      multimap<string,NcVar> vars=it->second.getVars(ChildrenAndCurrent);
+    for (auto group : getGroups()) {
+      multimap<string,NcVar> vars = group.second.getVars(ChildrenAndCurrent);
       ncVars.insert(vars.begin(),vars.end());
     }
   }
@@ -372,12 +366,10 @@ multimap<std::string,NcVar> NcGroup::getVars(NcGroup::Location location) const {
 // Get all NcVar objects with a given name.
 set<NcVar> NcGroup::getVars(const string& name,NcGroup::Location location) const {
   // get the set of ncVars in this group and above.
-  multimap<std::string,NcVar> ncVars(getVars(location));
-  pair<multimap<string,NcVar>::iterator,multimap<string,NcVar>::iterator> ret;
-  multimap<string,NcVar>::iterator it;
-  ret = ncVars.equal_range(name);
+  const auto ncVars(getVars(location));
+  const auto ret = ncVars.equal_range(name);
   set<NcVar> tmpVar;
-  for (it=ret.first; it!=ret.second; ++it) {
+  for (auto it=ret.first; it!=ret.second; ++it) {
     tmpVar.insert(it->second);
   }
   return tmpVar;
@@ -387,14 +379,12 @@ set<NcVar> NcGroup::getVars(const string& name,NcGroup::Location location) const
 
 // Get the named NcVar object.
 NcVar NcGroup::getVar(const string& name,NcGroup::Location location) const {
-  multimap<std::string,NcVar> ncVars(getVars(location));
-  pair<multimap<string,NcVar>::iterator,multimap<string,NcVar>::iterator> ret;
-  ret = ncVars.equal_range(name);
-  if(ret.first == ret.second)
+  const auto ret = getVars(location).equal_range(name);
+  if (ret.first == ret.second) {
     // no matching netCDF variable found so return null object.
     return NcVar();
-  else
-    return ret.first->second;
+  }
+  return ret.first->second;
 }
 
 // Adds a new netCDF scalar variable.
@@ -457,8 +447,8 @@ NcVar NcGroup::addVar(const string& name, const string& typeName, const vector<s
   // get a set of NcDim objects corresponding to the given dimension names.
   vector<int> dimIds;
   dimIds.reserve(dimNames.size());
-  for (size_t i=0; i<dimNames.size();i++){
-    NcDim tmpDim(getDim(dimNames[i],NcGroup::ParentsAndCurrent));
+  for (const auto& dimName : dimNames) {
+    NcDim tmpDim(getDim(dimName, NcGroup::ParentsAndCurrent));
     if(tmpDim.isNull()) throw NcNullDim("Attempt to invoke NcGroup::addVar failed: dimNames must be defined in either the current group or a parent group",__FILE__,__LINE__);
     dimIds.push_back(tmpDim.getId());
   }
@@ -481,12 +471,11 @@ NcVar NcGroup::addVar(const string& name, const NcType& ncType, const vector<NcD
   if(tmpType.isNull()) throw NcNullType("Attempt to invoke NcGroup::addVar failed: NcType must be defined in either the current group or a parent group",__FILE__,__LINE__);
 
   // check NcDim objects are valid
-  vector<NcDim>::const_iterator iter;
   vector<int> dimIds;
   dimIds.reserve(ncDimVector.size());
-  for (iter=ncDimVector.begin();iter < ncDimVector.end(); iter++) {
-    if(iter->isNull()) throw NcNullDim("Attempt to invoke NcGroup::addVar with a Null NcDim object",__FILE__,__LINE__);
-    NcDim tmpDim(getDim(iter->getName(),NcGroup::ParentsAndCurrent));
+  for (const auto& dim : ncDimVector) {
+    if(dim.isNull()) throw NcNullDim("Attempt to invoke NcGroup::addVar with a Null NcDim object",__FILE__,__LINE__);
+    NcDim tmpDim(getDim(dim.getName(),NcGroup::ParentsAndCurrent));
     if(tmpDim.isNull()) throw NcNullDim("Attempt to invoke NcGroup::addVar failed: NcDim must be defined in either the current group or a parent group",__FILE__,__LINE__);
     dimIds.push_back(tmpDim.getId());
   }
@@ -529,10 +518,8 @@ int NcGroup::getAttCount(NcGroup::Location location) const {
 
   // search recursively in all child groups
   if(location == ChildrenAndCurrent || location == Children || location == All) {
-    multimap<string,NcGroup>::iterator it;
-    multimap<string,NcGroup> groups(getGroups());
-    for (it=groups.begin();it!=groups.end();it++) {
-      ngatts += it->second.getAttCount(ChildrenAndCurrent);
+    for (const auto& group : getGroups()) {
+      ngatts += group.second.getAttCount(ChildrenAndCurrent);
     }
   }
 
@@ -554,8 +541,9 @@ multimap<std::string,NcGroupAtt> NcGroup::getAtts(NcGroup::Location location) co
     for(int i=0; i<attCount;i++){
       char charName[NC_MAX_NAME+1];
       ncCheck(nc_inq_attname(tmpGroup.getId(),NC_GLOBAL,i,charName),__FILE__,__LINE__);
-      NcGroupAtt tmpAtt(tmpGroup.getId(),i);
-      ncAtts.insert(pair<const string,NcGroupAtt>(string(charName),tmpAtt));
+      ncAtts.emplace(std::piecewise_construct,
+                     std::forward_as_tuple(charName),
+                     std::forward_as_tuple(tmpGroup, i));
     }
   }
 
@@ -569,8 +557,9 @@ multimap<std::string,NcGroupAtt> NcGroup::getAtts(NcGroup::Location location) co
       for(int i=0; i<attCount;i++){
         char charName[NC_MAX_NAME+1];
         ncCheck(nc_inq_attname(tmpGroup.getId(),NC_GLOBAL,i,charName),__FILE__,__LINE__);
-        NcGroupAtt tmpAtt(tmpGroup.getId(),i);
-        ncAtts.insert(pair<const string,NcGroupAtt>(string(charName),tmpAtt));
+        ncAtts.emplace(std::piecewise_construct,
+                       std::forward_as_tuple(charName),
+                       std::forward_as_tuple(tmpGroup, i));
       }
       // continue loop with the parent.
       tmpGroup=tmpGroup.getParentGroup();
@@ -579,10 +568,8 @@ multimap<std::string,NcGroupAtt> NcGroup::getAtts(NcGroup::Location location) co
 
   // search recusively in all child groups.
   if(location == ChildrenAndCurrent || location == Children  || location == All ) {
-    multimap<string,NcGroup>::iterator it;
-    multimap<string,NcGroup> groups(getGroups());
-    for (it=groups.begin();it!=groups.end();it++) {
-      multimap<string,NcGroupAtt> atts=it->second.getAtts(ChildrenAndCurrent);
+    for (const auto& group : getGroups()) {
+      const auto atts = group.second.getAtts(ChildrenAndCurrent);
       ncAtts.insert(atts.begin(),atts.end());
     }
   }
@@ -593,24 +580,21 @@ multimap<std::string,NcGroupAtt> NcGroup::getAtts(NcGroup::Location location) co
 // Get the named NcGroupAtt object.
 NcGroupAtt NcGroup::getAtt(const std::string& name,NcGroup::Location location) const {
   multimap<std::string,NcGroupAtt> ncAtts(getAtts(location));
-  pair<multimap<string,NcGroupAtt>::iterator,multimap<string,NcGroupAtt>::iterator> ret;
-  ret = ncAtts.equal_range(name);
-  if(ret.first == ret.second)
+  const auto ret = ncAtts.equal_range(name);
+  if (ret.first == ret.second) {
     // no matching groupAttribute so return null object.
     return NcGroupAtt();
-  else
-    return ret.first->second;
+  }
+  return ret.first->second;
 }
 
 // Get all NcGroupAtt objects with a given name.
 set<NcGroupAtt> NcGroup::getAtts(const string& name,NcGroup::Location location) const {
   // get the set of ncGroupAtts in this group and above.
-  multimap<std::string,NcGroupAtt> ncAtts(getAtts(location));
-  pair<multimap<string,NcGroupAtt>::iterator,multimap<string,NcGroupAtt>::iterator> ret;
-  multimap<string,NcGroupAtt>::iterator it;
-  ret = ncAtts.equal_range(name);
+  const auto ncAtts(getAtts(location));
+  const auto ret = ncAtts.equal_range(name);
   set<NcGroupAtt> tmpAtt;
-  for (it=ret.first; it!=ret.second; ++it) {
+  for (auto it=ret.first; it!=ret.second; ++it) {
     tmpAtt.insert(it->second);
   }
   return tmpAtt;
@@ -917,19 +901,15 @@ int NcGroup::getDimCount(NcGroup::Location location) const {
 
   // search in parent groups.
   if(location == Parents || location == ParentsAndCurrent || location == All ) {
-    multimap<string,NcGroup>::iterator it;
-    multimap<string,NcGroup> groups(getGroups(ParentsGrps));
-    for (it=groups.begin();it!=groups.end();it++) {
-      ndims += it->second.getDimCount();
+    for (const auto& group : getGroups(ParentsGrps)) {
+      ndims += group.second.getDimCount();
     }
   }
 
   // search in child groups.
   if(location == Children || location == ChildrenAndCurrent || location == All ) {
-    multimap<string,NcGroup>::iterator it;
-    multimap<string,NcGroup> groups(getGroups(AllChildrenGrps));
-    for (it=groups.begin();it!=groups.end();it++) {
-      ndims += it->second.getDimCount();
+    for (const auto& group : getGroups(AllChildrenGrps)) {
+      ndims += group.second.getDimCount();
     }
   }
   return ndims;
@@ -949,29 +929,25 @@ multimap<string,NcDim> NcGroup::getDims(NcGroup::Location location) const {
       vector<int> dimids(dimCount);
       ncCheck(nc_inq_dimids(getId(), nullptr, &dimids[0], 0),__FILE__,__LINE__);
       // now get the name of each NcDim and populate the nDims container.
-      for(std::size_t i=0; i<dimCount;i++){
-        NcDim tmpDim(*this,dimids[i]);
-        ncDims.insert(pair<const string,NcDim>(tmpDim.getName(),tmpDim));
+      for (auto dimid : dimids) {
+        NcDim tmpDim(*this,dimid);
+        ncDims.emplace(tmpDim.getName(), tmpDim);
       }
     }
   }
 
   // search in parent groups.
   if(location == Parents || location == ParentsAndCurrent || location == All ) {
-    multimap<string,NcGroup>::iterator it;
-    multimap<string,NcGroup> groups(getGroups(ParentsGrps));
-    for (it=groups.begin();it!=groups.end();it++) {
-      multimap<string,NcDim> dimTmp(it->second.getDims());
+    for (const auto& group: getGroups(ParentsGrps)) {
+      const auto dimTmp(group.second.getDims());
       ncDims.insert(dimTmp.begin(),dimTmp.end());
     }
   }
 
   // search in child groups (makes recursive calls).
   if(location == Children || location == ChildrenAndCurrent || location == All ) {
-    multimap<string,NcGroup>::iterator it;
-    multimap<string,NcGroup> groups(getGroups(AllChildrenGrps));
-    for (it=groups.begin();it!=groups.end();it++) {
-      multimap<string,NcDim> dimTmp(it->second.getDims());
+    for (const auto& group : getGroups(AllChildrenGrps)) {
+      const auto dimTmp(group.second.getDims());
       ncDims.insert(dimTmp.begin(),dimTmp.end());
     }
   }
@@ -985,12 +961,11 @@ multimap<string,NcDim> NcGroup::getDims(NcGroup::Location location) const {
 NcDim NcGroup::getDim(const string& name,NcGroup::Location location) const {
   if(isNull()) throw NcNullGrp("Attempt to invoke NcGroup::getDim on a Null group",__FILE__,__LINE__);
   multimap<string,NcDim> ncDims(getDims(location));
-  pair<multimap<string,NcDim>::iterator,multimap<string,NcDim>::iterator> ret;
-  ret = ncDims.equal_range(name);
-  if(ret.first == ret.second)
+  const auto ret = ncDims.equal_range(name);
+  if (ret.first == ret.second) {
     return NcDim(); // null group is returned
-  else
-    return ret.first->second;
+  }
+  return ret.first->second;
 }
 
 
@@ -998,12 +973,10 @@ NcDim NcGroup::getDim(const string& name,NcGroup::Location location) const {
 set<NcDim> NcGroup::getDims(const string& name,NcGroup::Location location) const {
   if(isNull()) throw NcNullGrp("Attempt to invoke NcGroup::getDims on a Null group",__FILE__,__LINE__);
   // get the set of ncDims in this group and above.
-  multimap<string,NcDim> ncDims(getDims(location));
-  pair<multimap<string,NcDim>::iterator,multimap<string,NcDim>::iterator> ret;
-  multimap<string,NcDim>::iterator it;
-  ret = ncDims.equal_range(name);
+  const auto ncDims(getDims(location));
+  const auto ret = ncDims.equal_range(name);
   set<NcDim> tmpDim;
-  for (it=ret.first; it!=ret.second; ++it) {
+  for (auto it=ret.first; it!=ret.second; ++it) {
     tmpDim.insert(it->second);
   }
   return tmpDim;
@@ -1055,19 +1028,15 @@ int NcGroup::getTypeCount(NcGroup::Location location) const {
 
   // search in parent groups.
   if(location == Parents || location == ParentsAndCurrent || location == All ) {
-    multimap<string,NcGroup>::iterator it;
-    multimap<string,NcGroup> groups(getGroups(ParentsGrps));
-    for (it=groups.begin();it!=groups.end();it++) {
-      ntypes += it->second.getTypeCount();
+    for (const auto& group : getGroups(ParentsGrps)) {
+      ntypes += group.second.getTypeCount();
     }
   }
 
   // search in child groups.
   if(location == Children || location == ChildrenAndCurrent || location == All ) {
-    multimap<string,NcGroup>::iterator it;
-    multimap<string,NcGroup> groups(getGroups(AllChildrenGrps));
-    for (it=groups.begin();it!=groups.end();it++) {
-      ntypes += it->second.getTypeCount();
+    for (const auto& group : getGroups(AllChildrenGrps)) {
+      ntypes += group.second.getTypeCount();
     }
   }
   return ntypes;
@@ -1091,8 +1060,8 @@ int NcGroup::getTypeCount(NcType::ncType enumType, NcGroup::Location location) c
     if (ntypesp){
       vector<int> typeids(static_cast<std::size_t>(ntypesp));
       ncCheck(nc_inq_typeids(getId(), &ntypesp,&typeids[0]),__FILE__,__LINE__);
-      for (std::size_t i=0; i<static_cast<std::size_t>(ntypesp); i++){
-        NcType tmpType(*this,typeids[i]);
+      for (auto typeid_ : typeids) {
+        NcType tmpType(*this, typeid_);
         if(tmpType.getTypeClass() == enumType) ntypes++;
       }
     }
@@ -1100,19 +1069,15 @@ int NcGroup::getTypeCount(NcType::ncType enumType, NcGroup::Location location) c
 
   // search in parent groups.
   if(location == Parents || location == ParentsAndCurrent || location == All ) {
-    multimap<string,NcGroup>::iterator it;
-    multimap<string,NcGroup> groups(getGroups(ParentsGrps));
-    for (it=groups.begin();it!=groups.end();it++) {
-      ntypes += it->second.getTypeCount(enumType);
+    for (const auto& group : getGroups(ParentsGrps)) {
+      ntypes += group.second.getTypeCount(enumType);
     }
   }
 
   // search in child groups.
   if(location == Children || location == ChildrenAndCurrent || location == All ) {
-    multimap<string,NcGroup>::iterator it;
-    multimap<string,NcGroup> groups(getGroups(AllChildrenGrps));
-    for (it=groups.begin();it!=groups.end();it++) {
-      ntypes += it->second.getTypeCount(enumType);
+    for (const auto& group : getGroups(AllChildrenGrps)) {
+      ntypes += group.second.getTypeCount(enumType);
     }
   }
   return ntypes;
@@ -1132,29 +1097,25 @@ multimap<string,NcType> NcGroup::getTypes(NcGroup::Location location) const {
       vector<int> typeids(typeCount);
       ncCheck(nc_inq_typeids(getId(), nullptr, &typeids[0]),__FILE__,__LINE__);
       // now get the name of each NcType and populate the nTypes container.
-      for(std::size_t i=0; i<typeCount;i++){
-        NcType tmpType(*this,typeids[i]);
-        ncTypes.insert(pair<const string,NcType>(tmpType.getName(),tmpType));
+      for (auto typeid_ : typeids) {
+        NcType tmpType(*this, typeid_);
+        ncTypes.emplace(tmpType.getName(), tmpType);
       }
     }
   }
 
   // search in parent groups.
   if(location == Parents || location == ParentsAndCurrent || location == All ) {
-    multimap<string,NcGroup>::iterator it;
-    multimap<string,NcGroup> groups(getGroups(ParentsGrps));
-    for (it=groups.begin();it!=groups.end();it++) {
-      multimap<string,NcType> typeTmp(it->second.getTypes());
+    for (const auto& group : getGroups(ParentsGrps)) {
+      multimap<string,NcType> typeTmp(group.second.getTypes());
       ncTypes.insert(typeTmp.begin(),typeTmp.end());
     }
   }
 
   // search in child groups (makes recursive calls).
   if(location == Children || location == ChildrenAndCurrent || location == All ) {
-    multimap<string,NcGroup>::iterator it;
-    multimap<string,NcGroup> groups(getGroups(AllChildrenGrps));
-    for (it=groups.begin();it!=groups.end();it++) {
-      multimap<string,NcType> typeTmp(it->second.getTypes());
+    for (const auto& group : getGroups(AllChildrenGrps)) {
+      multimap<string,NcType> typeTmp(group.second.getTypes());
       ncTypes.insert(typeTmp.begin(),typeTmp.end());
     }
   }
@@ -1166,17 +1127,12 @@ multimap<string,NcType> NcGroup::getTypes(NcGroup::Location location) const {
 // Gets the collection of NcType objects with a given name.
 set<NcType> NcGroup::getTypes(const string& name, NcGroup::Location location) const {
   if(isNull()) throw NcNullGrp("Attempt to invoke NcGroup::getTypes on a Null group",__FILE__,__LINE__);
-  // iterator for the multimap container.
-  multimap<string,NcType>::iterator it;
-  // return argument of equal_range: iterators to lower and upper bounds of the range.
-  pair<multimap<string,NcType>::iterator,multimap<string,NcType>::iterator> ret;
   // get the entire collection of types.
-  multimap<string,NcType> types(getTypes(location));
-  // define STL set object to hold the result
-  set<NcType> tmpType;
+  const auto types(getTypes(location));
   // get the set of NcType objects with a given name
-  ret=types.equal_range(name);
-  for (it=ret.first;it!=ret.second;it++) {
+  const auto ret = types.equal_range(name);
+  set<NcType> tmpType;
+  for (auto it=ret.first;it!=ret.second;it++) {
     tmpType.insert(it->second);
   }
   return tmpType;
@@ -1186,16 +1142,13 @@ set<NcType> NcGroup::getTypes(const string& name, NcGroup::Location location) co
 // Gets the collection of NcType objects with a given data type.
 set<NcType> NcGroup::getTypes(NcType::ncType enumType, NcGroup::Location location) const {
   if(isNull()) throw NcNullGrp("Attempt to invoke NcGroup::getTypes on a Null group",__FILE__,__LINE__);
-  // iterator for the multimap container.
-  multimap<string,NcType>::iterator it;
-  // get the entire collection of types.
-  multimap<string,NcType> types(getTypes(location));
+
   // define STL set object to hold the result
   set<NcType> tmpType;
   // get the set of NcType objects with a given data type
-  for (it=types.begin();it!=types.end();it++) {
-    if(it->second.getTypeClass() == enumType) {
-      tmpType.insert(it->second);
+  for (const auto& type : getTypes(location)) {
+    if (type.second.getTypeClass() == enumType) {
+      tmpType.insert(type.second);
     }
   }
   return(tmpType);
@@ -1205,18 +1158,15 @@ set<NcType> NcGroup::getTypes(NcType::ncType enumType, NcGroup::Location locatio
 // Gets the collection of NcType objects with a given name and data type.
 set<NcType> NcGroup::getTypes(const string& name, NcType::ncType enumType, NcGroup::Location location) const {
   if(isNull()) throw NcNullGrp("Attempt to invoke NcGroup::getTypes on a Null group",__FILE__,__LINE__);
-  // iterator for the multimap container.
-  multimap<string,NcType>::iterator it;
-  // return argument of equal_range: iterators to lower and upper bounds of the range.
-  pair<multimap<string,NcType>::iterator,multimap<string,NcType>::iterator> ret;
+
   // get the entire collection of types.
   multimap<string,NcType> types(getTypes(location));
   // define STL set object to hold the result
   set<NcType> tmpType;
   // get the set of NcType objects with a given name
-  ret=types.equal_range(name);
-  for (it=ret.first;it!=ret.second;it++) {
-    if((*it).second.getTypeClass() == enumType) {
+  const auto ret=types.equal_range(name);
+  for (auto it=ret.first;it!=ret.second;it++) {
+    if(it->second.getTypeClass() == enumType) {
       tmpType.insert(it->second);
     }
   }
@@ -1241,20 +1191,16 @@ NcType NcGroup::getType(const string& name, NcGroup::Location location) const {
   if(name ==  "string"  ) return ncString;
 
   // this is a user defined type
-  // iterator for the multimap container.
-  multimap<string,NcType>::iterator it;
-  // return argument of equal_range: iterators to lower and upper bounds of the range.
-  pair<multimap<string,NcType>::iterator,multimap<string,NcType>::iterator> ret;
   // get the entire collection of types.
   multimap<string,NcType> types(getTypes(location));
   // define STL set object to hold the result
   set<NcType> tmpType;
     // get the set of NcType objects with a given name
-  ret=types.equal_range(name);
-  if(ret.first == ret.second)
+  const auto ret=types.equal_range(name);
+  if(ret.first == ret.second) {
     return NcType();
-  else
-    return ret.first->second;
+  }
+  return ret.first->second;
 }
 
 
@@ -1303,8 +1249,6 @@ map<string,NcGroup> NcGroup::getCoordVars(NcGroup::Location location) const {
 
   // search in current group and parent groups.
   NcGroup tmpGroup(*this);
-  multimap<string,NcDim>::iterator itD;
-  multimap<string,NcVar>::iterator itV;
   bool check_current_group = !(location == Parents || location == Children);
   const bool check_parent_groups = (location == Parents || location == ParentsAndCurrent || location == All);
   const bool check_child_groups = (location == Children || location == ChildrenAndCurrent || location == All);
@@ -1312,13 +1256,12 @@ map<string,NcGroup> NcGroup::getCoordVars(NcGroup::Location location) const {
   while(1) {
     // get the collection of NcDim objects defined in this group.
     if (check_current_group) {
-      multimap<string,NcDim> dimTmp(tmpGroup.getDims());
       multimap<string,NcVar> varTmp(tmpGroup.getVars());
-      for (itD=dimTmp.begin();itD!=dimTmp.end();itD++) {
-        string coordName(itD->first);
-        itV = varTmp.find(coordName);
-        if(itV != varTmp.end()) {
-          coordVars.insert(pair<const string,NcGroup>(string(coordName),tmpGroup));
+      for (const auto& dim : tmpGroup.getDims()) {
+        string coordName(dim.first);
+        const auto var = varTmp.find(coordName);
+        if(var != varTmp.end()) {
+          coordVars.emplace(coordName, tmpGroup);
         }
       }
     }
@@ -1334,10 +1277,8 @@ map<string,NcGroup> NcGroup::getCoordVars(NcGroup::Location location) const {
 
   // search in child groups (makes recursive calls).
   if (check_child_groups) {
-    multimap<string,NcGroup>::iterator it;
-    multimap<string,NcGroup> groups(getGroups());
-    for (it=groups.begin();it!=groups.end();it++) {
-      map<string,NcGroup> coordVarsTmp = it->second.getCoordVars(ChildrenAndCurrent);
+    for (const auto& group : getGroups()) {
+      map<string,NcGroup> coordVarsTmp = group.second.getCoordVars(ChildrenAndCurrent);
       coordVars.insert(coordVarsTmp.begin(),coordVarsTmp.end());
     }
   }
@@ -1352,9 +1293,7 @@ void NcGroup::getCoordVar(const string& coordVarName, NcDim& ncDim, NcVar& ncVar
   ncVar = NcVar{};
 
   // search in current group and parent groups.
-  multimap<string,NcDim>::iterator itD;
   NcGroup tmpGroup(*this);
-  multimap<string,NcVar>::iterator itV;
   bool check_current_group = !(location == Parents || location == Children);
   const bool check_parent_groups = (location == Parents || location == ParentsAndCurrent || location == All);
   const bool check_child_groups = (location == Children || location == ChildrenAndCurrent || location == All);
@@ -1364,11 +1303,11 @@ void NcGroup::getCoordVar(const string& coordVarName, NcDim& ncDim, NcVar& ncVar
     if (check_current_group) {
       multimap<string,NcDim> dimTmp(tmpGroup.getDims());
       multimap<string,NcVar> varTmp(tmpGroup.getVars());
-      itD=dimTmp.find(coordVarName);
-      itV=varTmp.find(coordVarName);
-      if(itD != dimTmp.end() && itV != varTmp.end()) {
-        ncDim=itD->second;
-        ncVar=itV->second;
+      const auto dim = dimTmp.find(coordVarName);
+      const auto var = varTmp.find(coordVarName);
+      if(dim != dimTmp.end() && var != varTmp.end()) {
+        ncDim=dim->second;
+        ncVar=var->second;
         return;
       }
     }
@@ -1382,10 +1321,8 @@ void NcGroup::getCoordVar(const string& coordVarName, NcDim& ncDim, NcVar& ncVar
 
   // search in child groups (makes recursive calls).
   if (check_child_groups) {
-    multimap<string,NcGroup>::iterator it;
-    multimap<string,NcGroup> groups(getGroups());
-    for (it=groups.begin();it!=groups.end();it++) {
-      it->second.getCoordVar(coordVarName,ncDim,ncVar,ChildrenAndCurrent);
+    for (const auto& group : getGroups()) {
+      group.second.getCoordVar(coordVarName,ncDim,ncVar,ChildrenAndCurrent);
       if(!ncDim.isNull()) break;
     }
   }
diff --git a/cxx4/ncVar.cpp b/cxx4/ncVar.cpp
index 76d4feb..70f7f63 100644
--- a/cxx4/ncVar.cpp
+++ b/cxx4/ncVar.cpp
@@ -116,10 +116,9 @@ NcType NcVar::getType() const {
   if(xtypep ==  ncDouble.getId()  ) return ncDouble;
   if(xtypep ==  ncString.getId()  ) return ncString;
 
-  multimap<string,NcType>::const_iterator it;
   multimap<string,NcType> types(NcGroup(groupId).getTypes(NcGroup::ParentsAndCurrent));
-  for(it=types.begin(); it!=types.end(); it++) {
-    if(it->second.getId() == xtypep) return it->second;
+  for (const auto& type : types) {
+    if(type.second.getId() == xtypep) return type.second;
   }
   // we will never reach here
   return true;
@@ -159,8 +158,8 @@ vector<NcDim> NcVar::getDims() const
     vector<int> dimids(dimCount);
     ncCheck(nc_inq_vardimid(groupId,myId, &dimids[0]),__FILE__,__LINE__);
     ncDims.reserve(dimCount);
-    for (std::size_t i = 0; i < dimCount; i++) {
-      NcDim tmpDim(getParentGroup(),dimids[i]);
+    for (auto dimid : dimids) {
+      NcDim tmpDim(getParentGroup(), dimid);
       ncDims.push_back(tmpDim);
     }
   }
@@ -202,7 +201,7 @@ map<string,NcVarAtt> NcVar::getAtts() const
   map<string,NcVarAtt> ncAtts;
   for (int i=0; i<attCount; i++){
     NcVarAtt tmpAtt(getParentGroup(),*this,i);
-    ncAtts.insert(pair<const string,NcVarAtt>(tmpAtt.getName(),tmpAtt));
+    ncAtts.emplace(tmpAtt.getName(), tmpAtt);
   }
   return ncAtts;
 }
@@ -212,8 +211,7 @@ map<string,NcVarAtt> NcVar::getAtts() const
 NcVarAtt NcVar::getAtt(const string& name) const
 {
   map<string,NcVarAtt> attributeList = getAtts();
-  map<string,NcVarAtt>::iterator myIter;
-  myIter = attributeList.find(name);
+  const auto myIter = attributeList.find(name);
   if(myIter == attributeList.end()){
     string msg("Attribute '"+name+"' not found");
     throw NcException(msg.c_str(),__FILE__,__LINE__);