message: move back from string to char* in test
diff: @@ -138,7 +138,7 @@ public:
  int REDEFINE =
  0; // 1: delete and redefine variable definitions at each step to
  // test adios_delete_vardefs()
  - std::string FILENAME;
  + char FILENAME[256];
  /* Variables to write */
  int *a2 = nullptr;
  @@ -242,9 +242,16 @@ public:
  NBLOCKS = p.nblocks;
  NSTEPS = p.nsteps;
  REDEFINE = redefineVars;
  - FILENAME = "manyVars." + std::to_string(NVARS) + "_" +
  - std::to_string(NBLOCKS) + "_" + std::to_string(NSTEPS) +
  - "_" + (REDEFINE ? "redefine" : "") + ".bp";
  + if (REDEFINE)
  + {
  + snprintf(FILENAME, sizeof(FILENAME), "manyVars.%d_%d_%d.bp", NVARS,
  + NBLOCKS, NSTEPS);
  + }
  + else
  + {
  + snprintf(FILENAME, sizeof(FILENAME),
  + "manyVars.%d_%d_%d_redefine.bp", NVARS, NBLOCKS, NSTEPS);
  + }
  alloc_vars();
  adios2_adios *adiosH =
  @@ -259,7 +266,7 @@ public:
  NSTEPS);
  }
  - engineW = adios2_open(ioW, FILENAME.c_str(), adios2_mode_write);
  + engineW = adios2_open(ioW, FILENAME, adios2_mode_write);
  err = 0;
  for (i = 0; i < NSTEPS; i++)
  @@ -314,15 +321,14 @@ public:
  double tb, te;
  size_t count[2] = {ldim1, ldim2};
  - log("Write step %d to %s\n", step, FILENAME.c_str());
  + log("Write step %d to %s\n", step, FILENAME);
  tb = MPI_Wtime();
  adios2_begin_step(engineW, adios2_step_mode_append, 0.0);
  for (block = 0; block < NBLOCKS; block++)
  {
  v = VALUE(rank, step, block);
  - log(" Write block %d, value %d to %s\n", block, v,
  - FILENAME.c_str());
  + log(" Write block %d, value %d to %s\n", block, v, FILENAME);
  set_vars(step, block);
  size_t start[2] = {offs1, offs2};
  for (i = 0; i < NVARS; i++)
  @@ -365,19 +371,18 @@ public:
  reset_readvars();
  - log("Read and check data in %s\n", FILENAME.c_str());
  - adios2_engine *engineR =
  - adios2_open(ioR, FILENAME.c_str(), adios2_mode_read);
  + log("Read and check data in %s\n", FILENAME);
  + adios2_engine *engineR = adios2_open(ioR, FILENAME, adios2_mode_read);
  if (engineR == NULL)
  {
  - printE("Error at opening file %s for reading\n", FILENAME.c_str());
  + printE("Error at opening file %s for reading\n", FILENAME);
  return 1;
  }
  adios2_step_status status =
  adios2_begin_step(engineR, adios2_step_mode_next_available, 0.0);
  - log(" Check variable definitions... %s\n", FILENAME.c_str());
  + log(" Check variable definitions... %s\n", FILENAME);
  tb = MPI_Wtime();
  for (i = 0; i < NVARS; i++)
  {
  