Use calls to empty() where appropriate.

src/games/nash.cc

@@ -51,7 +51,7 @@ MixedStrategyDetailRenderer<T>::Render(const MixedStrategyProfile<T> &p_profile,
     for (Array<GameStrategyRep *>::const_iterator 
 	   strategy = player->Strategies().begin();
 	 strategy != player->Strategies().end(); ++strategy) {
-      if (strategy->GetLabel() != "") {
+      if (!strategy->GetLabel().empty()) {
 	m_stream << std::setw(8) << strategy->GetLabel() << "    ";
       }
       else {
@@ -96,13 +96,13 @@ BehavStrategyDetailRenderer<T>::Render(const MixedBehaviorProfile<T> &p_profile,
       for (int act = 1; act <= infoset->NumActions(); act++) {
 	GameAction action = infoset->GetAction(act);
 
-	if (infoset->GetLabel() != "") {
+	if (!infoset->GetLabel().empty()) {
 	  m_stream << std::setw(7) << infoset->GetLabel() << "    ";
 	}
 	else {
 	  m_stream << std::setw(7) << infoset->GetNumber() << "    ";
 	}
-	if (action->GetLabel() != "") {
+	if (!action->GetLabel().empty()) {
 	  m_stream << std::setw(7) << action->GetLabel() << "   ";
 	}
 	else {
@@ -129,13 +129,13 @@ BehavStrategyDetailRenderer<T>::Render(const MixedBehaviorProfile<T> &p_profile,
 
       for (int n = 1; n <= infoset->NumMembers(); n++) {
 	GameNode node = infoset->GetMember(n);
-	if (infoset->GetLabel() != "") {
+	if (!infoset->GetLabel().empty()) {
 	  m_stream << std::setw(7) << infoset->GetLabel() << "    ";
 	}
 	else {
 	  m_stream << std::setw(7) << infoset->GetNumber() << "    ";
 	}
-	if (node->GetLabel() != "") {
+	if (!node->GetLabel().empty()) {
 	  m_stream << std::setw(7) << node->GetLabel() << "   ";
 	}
 	else {

src/gui/dleditnode.cc

@@ -117,7 +117,7 @@ dialogEditNode::dialogEditNode(wxWindow *p_parent, Gambit::GameNode p_node)
   for (int outc = 1; outc <= efg->NumOutcomes(); outc++) {
     Gambit::GameOutcome outcome = efg->GetOutcome(outc);
     std::string item = Gambit::lexical_cast<std::string>(outc) + ": " + outcome->GetLabel();
-    if (item == "") {
+    if (item.empty()) {
       item = "Outcome" + Gambit::lexical_cast<std::string>(outc);
     }
 

src/gui/dlefgreveal.cc

@@ -49,7 +49,7 @@ gbtRevealMoveDialog::gbtRevealMoveDialog(wxWindow *p_parent,
 
   for (int pl = 1; pl <= m_doc->NumPlayers(); pl++) {
     Gambit::GamePlayer player = m_doc->GetGame()->GetPlayer(pl);
-    if (player->GetLabel() != "") {
+    if (player->GetLabel().empty()) {
       m_players.push_back(new wxCheckBox(this, wxID_ANY,
                                          wxString(player->GetLabel().c_str(),
                                                   *wxConvCurrent)));

src/gui/dlnashmon.cc

@@ -181,7 +181,7 @@ void gbtNashMonitorDialog::OnEndProcess(wxProcessEvent &p_event)
     wxString msg;
     msg << tis.ReadLine();
 
-    if (msg != wxT("")) {
+    if (!msg.empty()) {
       m_doc->DoAddOutput(*m_output, msg);
       m_countText->SetLabel(wxString::Format(wxT("Number of equilibria found so far: %d"), m_output->NumProfiles()));
     }

src/gui/gameframe.cc

@@ -324,7 +324,7 @@ void gbtGameFrame::OnUpdate()
   std::string gameTitle;
   gameTitle = m_doc->GetGame()->GetTitle();
 
-  if (m_doc->GetFilename() != wxT("")) {
+  if (!m_doc->GetFilename().empty()) {
     SetTitle(wxT("Gambit - [") + m_doc->GetFilename() +
 	     wxT("] ") +
 	     wxString(gameTitle.c_str(), *wxConvCurrent));
@@ -842,7 +842,7 @@ void gbtGameFrame::OnFileClose(wxCommandEvent &)
 
 void gbtGameFrame::OnFileSave(wxCommandEvent &p_event)
 {
-  if (p_event.GetId() == wxID_SAVEAS || m_doc->GetFilename() == wxT("")) {
+  if (p_event.GetId() == wxID_SAVEAS || m_doc->GetFilename().empty()) {
     wxFileDialog dialog(this, _("Choose file"),
 			wxPathOnly(m_doc->GetFilename()),
 			wxFileNameFromPath(m_doc->GetFilename()),

src/solvers/enummixed/enummixed.cc

@@ -33,7 +33,7 @@ using namespace Gambit::linalg;
 template <class T> List<List<MixedStrategyProfile<T> > > 
 EnumMixedStrategySolution<T>::GetCliques() const
 {
-  if (m_cliques1.size() == 0) {
+  if (m_cliques1.empty()) {
     // Cliques are generated on demand
     int n = m_node1.Length();
     if (m_node2.Length() != n)  throw DimensionException();

src/solvers/gtracer/aggame.cc

@@ -227,9 +227,9 @@ void aggame::payoffMatrix(cmatrix &dest, cvector &s, agg::AggNumber fuzz){
 
 
 	    //compute partial prob distributions
-	    if (tasks.size()==0 && spares.size()==0) continue; //nothing to be done for this row
+	    if (tasks.empty() && spares.empty()) continue; //nothing to be done for this row
 
-	    if(aggPtr->isPure[currNode]||tasks.size()==0){
+	    if(aggPtr->isPure[currNode]||tasks.empty()){
 	      computePartialP_PureNode(rown, act1,tasks);
 	    }else{//do bisection
 	      computePartialP_bisect(rown,act1,tasks.begin(),tasks.end(),aggPtr->Pr[rown]);
@@ -258,7 +258,7 @@ void aggame::payoffMatrix(cmatrix &dest, cvector &s, agg::AggNumber fuzz){
 	      }
 	      else {
                 for(p=tasks.begin();p!=tasks.end();++p){
-		  if(aggPtr->Pr[*p].size()==0){
+		  if(aggPtr->Pr[*p].empty()){
 		    std::cerr<<"AGG::payoffMatrix() ERROR for rown="
 		        <<rown<<" act1="<<act1<<" *p=" <<*p
 			     <<": the distribution should not be empty!"<<std::endl;
@@ -275,7 +275,7 @@ void aggame::payoffMatrix(cmatrix &dest, cvector &s, agg::AggNumber fuzz){
 	      //if spares not empty, we need to compute nondisturbed payoffs
 	      //which requires the distrib induced by everyone (except rown).
 	      //we store this distrib in Pr[rown][act1][rown]
-	      if (spares.size()>0){
+	      if (!spares.empty()){
 		//assert(tasks.size()>0);
 	    	  aggPtr->Pr[rown].reset();
 	    	  aggPtr->Pr[rown].multiply(
@@ -296,7 +296,7 @@ void aggame::payoffMatrix(cmatrix &dest, cvector &s, agg::AggNumber fuzz){
 	    agg::AggNumber undisturbedPayoff;
 	    bool hasUndisturbed=false;
 
-	    if(spares.size()>0){//for players in spares, we compute one undisturbed payoff
+	    if(!spares.empty()){//for players in spares, we compute one undisturbed payoff
 	      computeUndisturbedPayoff(undisturbedPayoff,hasUndisturbed,rown,act1, rown);
 	      for(p=spares.begin();p!=spares.end();++p)
 		for(act2=0;act2<aggPtr->actions[*p];act2++)

src/tools/enumpoly/gpoly.cc

@@ -31,7 +31,7 @@ template<> double gPoly<double>::String_Coeff(double nega)
     charnum++;
     GetChar();
   }
-  if (Coeff == "") return (nega);
+  if (Coeff.empty()) return nega;
   else return (nega * strtod(Coeff.c_str(), nullptr));
 }
 

src/tools/gt/nfggnm.cc

@@ -168,7 +168,7 @@ int main(int argc, char *argv[])
     NashGNMStrategySolver solver(renderer, verbose);
 
     List<MixedStrategyProfile<double> > perts;
-    if (startFile != "") {
+    if (!startFile.empty()) {
       std::ifstream startPerts(startFile.c_str());
       perts = ReadStrategyPerturbations(game, startPerts);
     }

src/tools/liap/liap.cc

@@ -205,7 +205,7 @@ int main(int argc, char *argv[])
     Game game = ReadGame(*input_stream);
     if (!game->IsTree() || useStrategic) {
       List<MixedStrategyProfile<double> > starts;
-      if (startFile != "") {
+      if (!startFile.empty()) {
 	std::ifstream startPoints(startFile.c_str());
 	starts = ReadStrategyProfiles(game, startPoints);
       }
@@ -224,7 +224,7 @@ int main(int argc, char *argv[])
     }
     else {
       List<MixedBehaviorProfile<double> > starts;
-      if (startFile != "") {
+      if (!startFile.empty()) {
 	std::ifstream startPoints(startFile.c_str());
 	starts = ReadBehaviorProfiles(game, startPoints);
       }

src/tools/logit/logit.cc

@@ -175,7 +175,7 @@ int main(int argc, char *argv[])
       throw UndefinedException("Computing equilibria of games with imperfect recall is not supported.");
     }
 
-    if (mleFile != "" && (!game->IsTree() || useStrategic)) {
+    if (!mleFile.empty() && (!game->IsTree() || useStrategic)) {
       MixedStrategyProfile<double> frequencies(game->NewMixedStrategyProfile(0.0));
       std::ifstream mleData(mleFile.c_str());
       ReadProfile(mleData, frequencies);

src/tools/simpdiv/nfgsimpdiv.cc

@@ -173,7 +173,7 @@ int main(int argc, char *argv[])
   try {
     Game game = ReadGame(*input_stream);
     List<MixedStrategyProfile<Rational> > starts;
-    if (startFile != "") {
+    if (!startFile.empty()) {
       std::ifstream startPoints(startFile.c_str());
       starts = ReadProfiles(game, startPoints);
     }