static char help[] = "Demonstrates PetscOptionsPush()/PetscOptionsPop().\n\n";

#include <petscsys.h>
#include <petscoptions.h>
int main(int argc, char **argv)
{
  PetscOptions opt1, opt2;
  PetscInt     int1, int2;
  PetscBool    flg1, flg2, flga, match;
  char         str[16];

  PetscFunctionBeginUser;
  PetscCall(PetscInitialize(&argc, &argv, NULL, help));

  PetscCall(PetscOptionsCreate(&opt1));
  PetscCall(PetscOptionsInsertString(opt1, "-testa a"));
  PetscCall(PetscOptionsPush(opt1));
  PetscCall(PetscOptionsSetValue(NULL, "-test1", "1"));
  PetscCall(PetscOptionsGetInt(NULL, NULL, "-test1", &int1, &flg1));
  PetscCheck(flg1 && int1 == 1, PETSC_COMM_WORLD, PETSC_ERR_PLIB, "Unable to locate option test1 or it has the wrong value");
  PetscCall(PetscOptionsGetString(NULL, NULL, "-testa", str, sizeof(str), &flga));
  PetscCall(PetscStrcmp(str, "a", &match));
  PetscCheck(flga && match, PETSC_COMM_WORLD, PETSC_ERR_PLIB, "Unable to locate option testa or it has the wrong value");
  PetscCall(PetscOptionsCreate(&opt2));
  PetscCall(PetscOptionsPush(opt2));
  PetscCall(PetscOptionsSetValue(NULL, "-test2", "2"));
  PetscCall(PetscOptionsGetInt(NULL, NULL, "-test2", &int2, &flg2));
  PetscCheck(flg2 && int2 == 2, PETSC_COMM_WORLD, PETSC_ERR_PLIB, "Unable to locate option test2 or it has the wrong value");
  PetscCall(PetscOptionsGetInt(NULL, NULL, "-test1", &int1, &flg1));
  PetscCheck(!flg1, PETSC_COMM_WORLD, PETSC_ERR_PLIB, "Able to access test1 from a different options database");

  PetscCall(PetscOptionsPop());
  PetscCall(PetscOptionsPop());
  PetscCall(PetscOptionsDestroy(&opt2));
  PetscCall(PetscOptionsDestroy(&opt1));
  PetscCall(PetscFinalize());
  return 0;
}

/*TEST

   test:
     output_file: output/empty.out

TEST*/