Merge pull request #5945 from bangerth/avoid-stringstreams

Avoid where possible to use std::ostringstream to generate filenames.

examples/step-13/step-13.cc

@@ -55,7 +55,6 @@
 #include <iostream>
 #include <fstream>
 #include <list>
-#include <sstream>
 
 // The last step is as in all previous programs:
 namespace Step13
@@ -392,13 +391,13 @@ namespace Step13
     {}
 
 
-    // After the description above, the function generating the actual output
+    // Following the description above, the function generating the actual output
     // is now relatively straightforward. The only particularly interesting
     // feature over previous example programs is the use of the
     // DataOutBase::default_suffix function, returning the usual
     // suffix for files of a given format (e.g. ".eps" for encapsulated
     // postscript files, ".gnuplot" for Gnuplot files), and of the generic
-    // <code>DataOut::write</code> function with a second argument, which
+    // DataOut::write() function with a second argument, which internally
     // branches to the actual output functions for the different graphics
     // formats, based on the value of the format descriptor passed as second
     // argument.
@@ -418,12 +417,10 @@ namespace Step13
       data_out.add_data_vector (solution, "solution");
       data_out.build_patches ();
 
-      std::ostringstream filename;
-      filename << output_name_base << "-"
-               << this->refinement_cycle
-               << data_out.default_suffix (output_format)
-               << std::ends;
-      std::ofstream out (filename.str().c_str());
+      std::ofstream out (output_name_base
+                         + "-"
+                         + std::to_string(this->refinement_cycle)
+                         + data_out.default_suffix (output_format));
 
       data_out.write (out, output_format);
     }

examples/step-14/step-14.cc

@@ -54,7 +54,6 @@
 #include <list>
 #include <algorithm>
 #include <numeric>
-#include <sstream>
 
 // The last step is as in all previous programs:
 namespace Step14
@@ -344,13 +343,10 @@ namespace Step14
     GridOutput<dim>::operator () (const DoFHandler<dim> &dof_handler,
                                   const Vector<double>  &/*solution*/) const
     {
-      std::ostringstream filename;
-      filename << output_name_base << "-"
-               << this->refinement_cycle
-               << ".eps"
-               << std::ends;
-
-      std::ofstream out (filename.str().c_str());
+      std::ofstream out (output_name_base
+                         + "-"
+                         + std::to_string(this->refinement_cycle)
+                         + ".eps");
       GridOut().write_eps (dof_handler.get_triangulation(), out);
     }
   }
@@ -802,13 +798,9 @@ namespace Step14
       data_out.add_data_vector (this->solution, "solution");
       data_out.build_patches ();
 
-      std::ostringstream filename;
-      filename << "solution-"
-               << this->refinement_cycle
-               << ".gnuplot"
-               << std::ends;
-
-      std::ofstream out (filename.str().c_str());
+      std::ofstream out ("solution-"
+                         + std::to_string(this->refinement_cycle)
+                         + ".gnuplot");
       data_out.write (out, DataOutBase::gnuplot);
     }
 
@@ -2260,13 +2252,9 @@ namespace Step14
 
       data_out.build_patches ();
 
-      std::ostringstream filename;
-      filename << "solution-"
-               << this->refinement_cycle
-               << ".gnuplot"
-               << std::ends;
-
-      std::ofstream out (filename.str().c_str());
+      std::ofstream out ("solution-"
+                         + std::to_string(this->refinement_cycle)
+                         + ".gnuplot");
       data_out.write (out, DataOutBase::gnuplot);
     }
 

examples/step-16/step-16.cc

@@ -88,7 +88,6 @@
 // This is C++:
 #include <iostream>
 #include <fstream>
-#include <sstream>
 
 using namespace dealii;
 
@@ -591,12 +590,9 @@ namespace Step16
     data_out.add_data_vector (solution, "solution");
     data_out.build_patches ();
 
-    std::ostringstream filename;
-    filename << "solution-"
-             << cycle
-             << ".vtk";
-
-    std::ofstream output (filename.str().c_str());
+    std::ofstream output ("solution-"
+                          + std::to_string(cycle)
+                          + ".vtk");
     data_out.write_vtk (output);
   }
 

examples/step-17/step-17.cc

@@ -88,7 +88,6 @@
 // And this is simply C++ again:
 #include <fstream>
 #include <iostream>
-#include <sstream>
 
 // The last step is as in all previous programs:
 namespace Step17
@@ -941,17 +940,12 @@ namespace Step17
 
     // This being done, process zero goes ahead with setting up the
     // output file as in step-8, and attaching the (localized)
-    // solution vector to the output object. (The code to generate the
-    // output file name is stolen and slightly modified from step-5,
-    // since we expect that we can do a number of cycles greater than
-    // 10, which is the maximum of what the code in step-8 could
-    // handle.)
+    // solution vector to the output object.
     if (this_mpi_process == 0)
       {
-        std::ostringstream filename;
-        filename << "solution-" << cycle << ".vtk";
-
-        std::ofstream output (filename.str().c_str());
+        std::ofstream output ("solution-"
+                              + std::to_string(cycle)
+                              + ".vtk");
 
         DataOut<dim> data_out;
         data_out.attach_dof_handler (dof_handler);

examples/step-21/step-21.cc

@@ -59,7 +59,6 @@
 
 #include <iostream>
 #include <fstream>
-#include <sstream>
 
 // In this program, we use a tensor-valued coefficient. Since it may have a
 // spatial dependence, we consider it a tensor-valued function. The following
@@ -1086,7 +1085,14 @@ namespace Step21
   // @sect4{TwoPhaseFlowProblem::output_results}
 
   // There is nothing surprising here. Since the program will do a lot of time
-  // steps, we create an output file only every fifth time step.
+  // steps, we create an output file only every fifth time step and skip all
+  // other time steps at the top of the file already.
+  //
+  // When creating file names for output close to the bottom of the function,
+  // we convert the number of the time step to a string representation that
+  // is padded by leading zeros to four digits. We do this because this way
+  // all output file names have the same length, and consequently sort well
+  // when creating a directory listing.
   template <int dim>
   void TwoPhaseFlowProblem<dim>::output_results ()  const
   {
@@ -1122,12 +1128,9 @@ namespace Step21
 
     data_out.build_patches (degree+1);
 
-    std::ostringstream filename;
-    filename << "solution-"
-             << Utilities::int_to_string(timestep_number,4)
-             << ".vtk";
-
-    std::ofstream output (filename.str().c_str());
+    std::ofstream output ("solution-"
+                          + Utilities::int_to_string(timestep_number,4)
+                          + ".vtk");
     data_out.write_vtk (output);
   }
 

examples/step-22/step-22.cc

@@ -67,7 +67,6 @@
 #include <iostream>
 #include <fstream>
 #include <memory>
-#include <sstream>
 
 // As in all programs, the namespace dealii is included:
 namespace Step22
@@ -845,9 +844,9 @@ namespace Step22
   // <code>DataComponentInterpretation</code> namespace: as with the filename,
   // we create a vector in which the first <code>dim</code> components refer
   // to the velocities and are given the tag
-  // <code>DataComponentInterpretation::component_is_part_of_vector</code>; we
+  // DataComponentInterpretation::component_is_part_of_vector; we
   // finally push one tag
-  // <code>DataComponentInterpretation::component_is_scalar</code> to describe
+  // DataComponentInterpretation::component_is_scalar to describe
   // the grouping of the pressure variable.
 
   // The rest of the function is then the same as in step-20.
@@ -871,12 +870,9 @@ namespace Step22
                               data_component_interpretation);
     data_out.build_patches ();
 
-    std::ostringstream filename;
-    filename << "solution-"
-             << Utilities::int_to_string (refinement_cycle, 2)
-             << ".vtk";
-
-    std::ofstream output (filename.str().c_str());
+    std::ofstream output ("solution-"
+                          + Utilities::int_to_string(refinement_cycle, 2)
+                          + ".vtk");
     data_out.write_vtk (output);
   }
 

examples/step-31/step-31.cc

@@ -70,7 +70,6 @@
 #include <iostream>
 #include <fstream>
 #include <memory>
-#include <sstream>
 #include <limits>
 
 
@@ -1942,8 +1941,8 @@ namespace Step31
   // using the DataComponentInterpretation helper class. Next, we actually
   // attach the data vectors with their DoFHandler objects, build patches
   // according to the degree of freedom, which are (sub-) elements that
-  // describe the data for visualization programs. Finally, we set a file name
-  // (that includes the time step number) and write the vtk file.
+  // describe the data for visualization programs. Finally, we open a file
+  // (that includes the time step number) and write the vtk data into it.
   template <int dim>
   void BoussinesqFlowProblem<dim>::output_results ()  const
   {
@@ -1966,10 +1965,9 @@ namespace Step31
                               "T");
     data_out.build_patches (std::min(stokes_degree, temperature_degree));
 
-    std::ostringstream filename;
-    filename << "solution-" << Utilities::int_to_string(timestep_number, 4) << ".vtk";
-
-    std::ofstream output (filename.str().c_str());
+    std::ofstream output ("solution-"
+                          + Utilities::int_to_string(timestep_number,4)
+                          + ".vtk");
     data_out.write_vtk (output);
   }
 

examples/step-37/step-37.cc

@@ -58,7 +58,6 @@
 
 #include <iostream>
 #include <fstream>
-#include <sstream>
 
 
 namespace Step37
@@ -1129,29 +1128,23 @@ namespace Step37
     data_out.add_data_vector (solution, "solution");
     data_out.build_patches ();
 
-    std::ostringstream filename;
-    filename << "solution-"
-             << cycle
-             << "." << Utilities::MPI::this_mpi_process(MPI_COMM_WORLD)
-             << ".vtu";
-
-    std::ofstream output (filename.str().c_str());
+    std::ofstream output ("solution-"
+                          + std::to_string(cycle)
+                          + "."
+                          + std::to_string(Utilities::MPI::this_mpi_process(MPI_COMM_WORLD))
+                          + ".vtu");
     data_out.write_vtu (output);
 
     if (Utilities::MPI::this_mpi_process(MPI_COMM_WORLD) == 0)
       {
         std::vector<std::string> filenames;
         for (unsigned int i=0; i<Utilities::MPI::n_mpi_processes(MPI_COMM_WORLD); ++i)
-          {
-            std::ostringstream filename;
-            filename << "solution-"
-                     << cycle
-                     << "."
-                     << i
-                     << ".vtu";
-
-            filenames.push_back(filename.str().c_str());
-          }
+          filenames.emplace_back("solution-"
+                                 + std::to_string(cycle)
+                                 + "."
+                                 + std::to_string(i)
+                                 + ".vtu");
+
         std::string master_name = "solution-" + Utilities::to_string(cycle) + ".pvtu";
         std::ofstream master_output (master_name.c_str());
         data_out.write_pvtu_record (master_output, filenames);

examples/step-44/step-44.cc

@@ -3384,10 +3384,11 @@ namespace Step44
     MappingQEulerian<dim> q_mapping(degree, dof_handler_ref, soln);
     data_out.build_patches(q_mapping, degree);
 
-    std::ostringstream filename;
-    filename << "solution-" << dim << "d-" << time.get_timestep() << ".vtk";
-
-    std::ofstream output(filename.str().c_str());
+    std::ofstream output ("solution-"
+                          + std::to_string(dim)
+                          + "d-"
+                          + std::to_string(time.get_timestep())
+                          + ".vtk");
     data_out.write_vtk(output);
   }
 

examples/step-45/step-45.cc

@@ -676,14 +676,11 @@ namespace Step45
     data_out.add_data_vector (subdomain, "subdomain");
     data_out.build_patches (mapping, degree+1);
 
-    std::ostringstream filename;
-    filename << "solution-"
-             << Utilities::int_to_string (refinement_cycle, 2)
-             << "."
-             << Utilities::int_to_string (triangulation.locally_owned_subdomain(),2)
-             << ".vtu";
-
-    std::ofstream output (filename.str().c_str());
+    std::ofstream output ("solution-"
+                          + Utilities::int_to_string(refinement_cycle, 2)
+                          + "."
+                          + Utilities::int_to_string (triangulation.locally_owned_subdomain(),2)
+                          + ".vtu");
     data_out.write_vtu (output);
 
     if (Utilities::MPI::this_mpi_process(MPI_COMM_WORLD) == 0)

examples/step-46/step-46.cc

@@ -60,7 +60,6 @@
 
 #include <iostream>
 #include <fstream>
-#include <sstream>
 
 
 namespace Step46
@@ -910,12 +909,9 @@ namespace Step46
                               data_component_interpretation);
     data_out.build_patches ();
 
-    std::ostringstream filename;
-    filename << "solution-"
-             << Utilities::int_to_string (refinement_cycle, 2)
-             << ".vtk";
-
-    std::ofstream output (filename.str().c_str());
+    std::ofstream output ("solution-"
+                          + Utilities::int_to_string(refinement_cycle, 2)
+                          + ".vtk");
     data_out.write_vtk (output);
   }