diff --git a/FWI/src/FWINonlinearSolvers.cpp b/FWI/src/FWINonlinearSolvers.cpp
index 20823b2b42a6f0982d17eae0cd71fad1665a32bd..907e49df0c98bea843ff0d948d839b797460b6eb 100644
--- a/FWI/src/FWINonlinearSolvers.cpp
+++ b/FWI/src/FWINonlinearSolvers.cpp
@@ -277,8 +277,8 @@ public:
 
           if (iter % plotIter == 0 && (plotShot < 0 || prob == plotShot)) {
             FWD.plot(iterateNonlinear,
-                     "_fwi_" + Name() + nameSuff + "_iterate_m_" + to_string(prob) + "_" +
-                         to_string(iter),
+                     "_fwi_" + Name() + nameSuff + "_iterate_m_" +
+                         std::to_string(prob) + "_" + std::to_string(iter),
                      -1);
             FWD.plot(iterateNonlinear, "_fwi_" + Name() + nameSuff + "_iterate_m_" + "_",
                      all_shots_iter);
@@ -303,9 +303,10 @@ public:
 
     NonlinearOutput output;
     for (size_t prob = 0; prob < num_probs; ++prob) {
-      std::string shotStr = "NonlinearResiduals Shot " + to_string(prob);
+      std::string shotStr = "NonlinearResiduals Shot " + std::to_string(prob);
       mout.printEntryRaw(shotStr, regs[prob].GetResNormVector(0));
-      std::string nrOfInnerStr = "Inner Iterations Shot " + to_string(prob);
+      std::string nrOfInnerStr =
+          "Inner Iterations Shot " + std::to_string(prob);
       mout.printEntryRaw(nrOfInnerStr, regs[prob].GetInnerIters());
       output.push_back(regs[prob].GetResNormVector(0));
     }
@@ -355,7 +356,7 @@ public:
     if (fwiverbose >= 2)
       FWD.plot(iterateUpdatePN,
                "_fwi_" + Name() + nameSuff + "Gradient_OUTER_" +
-                   to_string(iter) + "_INNER_" + to_string(innerIter),
+                   std::to_string(iter) + "_INNER_" + std::to_string(innerIter),
                -1);
     MOUT(FWD.ScalarProductL2(iterateUpdatePN, iterateUpdatePN));
     initializePreconditioner(iterateNonlinear, nonlinearEvaluation,
@@ -387,8 +388,8 @@ public:
     iterateUpdatePNMinus1 = iterateUpdatePN;
     if (fwiverbose >= 2)
       FWD.plot(iterateUpdatePN,
-               "_fwi_" + Name() + nameSuff + "Iter_OUTER_" + to_string(iter) +
-                   "_INNER_" + to_string(innerIter),
+               "_fwi_" + Name() + nameSuff + "Iter_OUTER_" +
+                   std::to_string(iter) + "_INNER_" + std::to_string(innerIter),
                -1);
     return sqrt(FWD.ScalarProductL2(defectLinearized, defectLinearized));
   }
diff --git a/FWI/src/FWIRandomMains.cpp b/FWI/src/FWIRandomMains.cpp
index da56be65b2c88cd9fa3f80e7150eb6390c6fa5ab..90311c686a2a4a6a332771588b90eb2e520dcde4 100644
--- a/FWI/src/FWIRandomMains.cpp
+++ b/FWI/src/FWIRandomMains.cpp
@@ -76,8 +76,9 @@ int FWIConv() {
       assembleCombined->SetInitialValue(U_m[0]);
       TSolveR.SolveAndMeasure(assembleCombined, *Obs, s_m, &U_m);
       s_ms.push_back(s_m);
-//      s_m.collect();
-//      s_m.writeToFile(l+"S__deg_" + to_string(deg)+"__lv_" + to_string(lv) + "__freq_" + to_string(signalFreq));
+      //      s_m.collect();
+      //      s_m.writeToFile(l+"S__deg_" +  std::to_string(deg)+"__lv_" +
+      //      std::to_string(lv) + "__freq_" +  std::to_string(signalFreq));
     }
   }
   for (int i = 1; i < s_ms.size();++i){
diff --git a/FWI/src/FWI_DGTS.cpp b/FWI/src/FWI_DGTS.cpp
index c8c50af1cdcb81a3a13c0212864faf5b95579549..517769c0080c23417b08936ad640db5af66ef6be 100644
--- a/FWI/src/FWI_DGTS.cpp
+++ b/FWI/src/FWI_DGTS.cpp
@@ -325,7 +325,7 @@ std::vector<NonlinearOutput> FWIInverseMainDGTSVA() {
           }
           obs[i].getSeismogram().WriteToFile(
               Config::GetDataPath() + std::string("FWI/ObsFilteredShot") +
-              to_string(i) + Conf.SConf.FilteringType + s);
+              std::to_string(i) + Conf.SConf.FilteringType + s);
         }
       }
       if (!Conf.SConf.SrcInversion) {
@@ -371,7 +371,7 @@ std::vector<NonlinearOutput> FWIInverseMainDGTSVA() {
       mout << "The residuals are:" << endl;
       const NonlinearOutput &CurrentOutput = Output.back();
       for (int shot = 0; shot < CurrentOutput.size(); ++shot) {
-        mout << "Residuals of shot " + to_string(shot) << endl;
+        mout << "Residuals of shot " + std::to_string(shot) << endl;
         for (const auto &Result : CurrentOutput[shot]) {
           mout << Result << endl;
         }
@@ -470,7 +470,7 @@ int createKernels2() {
       }
     }
     AdjOp.CalculateAdjoint(Seis, Eval, nullptr);
-    auto &Plot = mpp::plot("Kernel_" + to_string(count));
+    auto &Plot = mpp::plot("Kernel_" + std::to_string(count));
     Plot.AddData("Rho", Eval, 0);
     Plot.AddData("Vp", Eval, 1);
     if (numL > 0) {
diff --git a/FWI/src/Helper/ABCHandler.cpp b/FWI/src/Helper/ABCHandler.cpp
index 976a80ec0c051110e4962036c416ca674b04f4e5..1aa383c47dfbce4847b98d062e66af4c46cfa6a1 100644
--- a/FWI/src/Helper/ABCHandler.cpp
+++ b/FWI/src/Helper/ABCHandler.cpp
@@ -359,7 +359,7 @@ void ABCHandler::InitializeBoundaryCellToTransferNEW(
         Point PMLPoint;
         FoundBuff.Receive(q) >> PMLPoint;
         if(!LostPoints.contains(PMLPoint)){
-          THROW("ERROR!!" + to_string(PPM->Proc()));
+          THROW("ERROR!!" + std::to_string(PPM->Proc()));
         }else {
           LostPoints.erase(PMLPoint);
           BondaryCellToTransfer[BorderPoint].emplace_back(PMLPoint, q);
@@ -453,7 +453,7 @@ void ABCHandler::InitializeCellToTransfer(
         Point CellPoint;
         FoundBuff.Receive(q) >> CellPoint;
         if(!LostPoints.contains(CellPoint)){
-          THROW("ERROR!!" + to_string(PPM->Proc()));
+          THROW("ERROR!!" + std::to_string(PPM->Proc()));
         }else {
           LostPoints.erase(CellPoint);
           CellToTransfer[CellPoint] = std::pair<short, short>(PPM->Proc(),q);
@@ -581,7 +581,8 @@ void ABCMatVectorFWI::communicateImpedanceFactors(ExchangeBuffer &exBuffer) {
             int i = Id(ReceivePoint);
           if constexpr (DebugLevel > 0) {
                 if (exBuffer.Receive(q).size() + Dof(i) >= exBuffer.ReceiveSize(q)) {
-                    Exit(to_string(PPM->Proc(CommSplit())) + ": Out of bounds.");
+                  Exit(std::to_string(PPM->Proc(CommSplit())) +
+                       ": Out of bounds.");
                 }
             }
             Point SendPoint;
@@ -706,7 +707,7 @@ void ABCHandlerAAO::InitializeBoundaryCellToTransferAAO(
         Point PMLPoint;
         FoundBuff.Receive(q) >> PMLPoint;
         if(!LostPoints.contains(PMLPoint)){
-          THROW("ERROR!!" + to_string(PPM->Proc()));
+          THROW("ERROR!!" + std::to_string(PPM->Proc()));
         }else {
           LostPoints.erase(PMLPoint);
           BondaryCellToTransfer[BorderPoint].emplace_back(PMLPoint, q);
diff --git a/FWI/src/Helper/ABCHandler.hpp b/FWI/src/Helper/ABCHandler.hpp
index ad7c1457fc9ccad64ed055939761119123bf190b..c24341a35138b644c21cd020b0b42d1a5b30c5af 100644
--- a/FWI/src/Helper/ABCHandler.hpp
+++ b/FWI/src/Helper/ABCHandler.hpp
@@ -296,8 +296,9 @@ public:
         exBuffer.Send(receiveProc) << ReceivePoint;
         bool found = Vec.find_cell(SendPoint) != Vec.cells_end();
         if (!found){
-          THROW("Point" + to_string(SendPoint[0]) + " " + to_string(SendPoint[1])
-                + " not found on proc " + to_string(PPM->Proc()));
+          THROW("Point" + std::to_string(SendPoint[0]) + " " +
+                std::to_string(SendPoint[1]) + " not found on proc " +
+                std::to_string(PPM->Proc()));
         }
         int i = Vec.Id(SendPoint);
         for (int k = 0; k < Vec.Dof(i); ++k) {
diff --git a/FWI/src/Helper/FWIHelpers.cpp b/FWI/src/Helper/FWIHelpers.cpp
index 4a5a4b09114dc26598ea7d22df31844d2d3e39ca..eaebfa5ce57fd631a253cdad4f2b5fadbfff00f4 100644
--- a/FWI/src/Helper/FWIHelpers.cpp
+++ b/FWI/src/Helper/FWIHelpers.cpp
@@ -100,7 +100,7 @@ void fillQuadrature(RVector &c, RVector &b, int order) {
       b[0] = 0.5;
       b[1] = 0.5;
   } else {
-      Exit("RKorder " + to_string(order) + " Not implemented");
+    Exit("RKorder " + std::to_string(order) + " Not implemented");
   }
 }
 
@@ -287,7 +287,7 @@ SourceConf::SourceConf() {
           Exit("No text-file found at: " + FrequencyFile)
         }
         std::string line;
-        std::vector<vector<double>> FrequencyLevelsTmp;
+        std::vector<std::vector<double>> FrequencyLevelsTmp;
         while (getline(file, line)) {
           trim(line);
           if (line.empty()) {
diff --git a/FWI/src/Problems/FWIAcousticInversionProb.cpp b/FWI/src/Problems/FWIAcousticInversionProb.cpp
index 98a9fc4cd01902828504854df39c4d4def74349a..16ef98a3086664c722fc39ee678dc501e1cf5342 100644
--- a/FWI/src/Problems/FWIAcousticInversionProb.cpp
+++ b/FWI/src/Problems/FWIAcousticInversionProb.cpp
@@ -76,6 +76,7 @@ void SourceInversionProblem(const std::vector<FWIDataContainerRange> &obs,
     SourceWaveletBase& Wavelet = prob->GetTimeSourceRef();
     SourceInversion(obs[shot].getSeismogram(), obsFwd[shot].getSeismogram(), src, Wavelet, &obsOp.GetSpaceOp(),
                     eps,Kappa);
-    Wavelet.WriteToFile(Config::GetDataPath() + "InvSourcetime_iter_" + to_string(j)  +"shot_"+  to_string(shot));
+    Wavelet.WriteToFile(Config::GetDataPath() + "InvSourcetime_iter_" +
+                        std::to_string(j) + "shot_" + std::to_string(shot));
   }
 }
diff --git a/FWI/src/Problems/FWIInversionProblems.cpp b/FWI/src/Problems/FWIInversionProblems.cpp
index 9732474ba4588f68b02549f3b123b4e736960c15..5bc9e067037f10534533900fb0dab7c3207fb433 100644
--- a/FWI/src/Problems/FWIInversionProblems.cpp
+++ b/FWI/src/Problems/FWIInversionProblems.cpp
@@ -361,7 +361,8 @@ public:
       srcSignals.emplace_back(std::make_unique<SourceWaveletBase>(*wav));
     }
     for (int i = 0; i<s;++i){
-      srcSignals[i]->WriteToFile(Config::GetDataPath()+ "SRC" + to_string(i));
+      srcSignals[i]->WriteToFile(Config::GetDataPath() + "SRC" +
+                                 std::to_string(i));
     }
   }
   double ForceP_i(double t, const Cell &c, const Point &z, int n, int) const override {