simple_xy_wr_formats.cpp

/* This is part of the netCDF package.
   Copyright 2006 University Corporation for Atmospheric Research/Unidata.
   See COPYRIGHT file for conditions of use.
 
   This is a very simple example which writes a 2D array of
   sample data. To handle this in netCDF we create two shared
   dimensions, "x" and "y", and a netCDF variable, called "data".
 
   This example is part of the netCDF tutorial:
   https://docs.unidata.ucar.edu/netcdf-c/current/tutorial_8dox.html
 
   Full documentation of the netCDF C++ API can be found at:
   https://docs.unidata.ucar.edu/netcdf-cxx
 
   $Id: simple_xy_wr_formats.cpp,v 1.1 2010/04/09 02:15:05 russ Exp $
*/
 
#include <iostream>
#include <netcdf>
#include <vector>
using namespace std;
using namespace netCDF;
using namespace netCDF::exceptions;
 
// We are writing 2D data, a 6 x 12 grid. 
static const int NX = 6;
static const int NY = 12;
 
// Return this in event of a problem.
static const int NC_ERR = 2;
 
int create_file(string filename, NcFile::FileFormat format) {
  // This is the data array we will write. It will just be filled
  // with a progression of numbers for this example.
  int dataOut[NX][NY];
  
  // Create some pretend data. If this wasn't an example program, we
  // would have some real data to write, for example, model output.
  for(int i = 0; i < NX; i++)
    for(int j = 0; j < NY; j++)
      dataOut[i][j] = i * NY + j;
  // The default behavior of the C++ API is to throw an exception i
  // an error occurs. A try catch block is necessary.
  try
    {  
      // Create the file. The Replace parameter tells netCDF to overwrite
      // this file, if it already exists.  The classic parameter specifies
      // that the file ceated should be in classic format, rather than the
      // default netCDF-4 format used by the cxx4 interface.
      NcFile dataFile(filename, NcFile::replace, format);
      
      // Create netCDF dimensions
      NcDim xDim = dataFile.addDim("x", NX);
      NcDim yDim = dataFile.addDim("y", NY);
      
      // Define the variable. The type of the variable in this case is
      // ncInt (32-bit integer).
      vector<NcDim> dims;
      dims.push_back(xDim);
      dims.push_back(yDim);
      NcVar data = dataFile.addVar("data", ncInt, dims);
   
      // In the classic model, must explicitly leave define mode
      // before writing data.  Need a method that calls nc_enddef().
      if(format != NcFile::nc4)
      dataFile.enddef();
 
      // Write the data to the file. Although netCDF supports
      // reading and writing subsets of data, in this case we write all
      // the data in one operation.
      data.putVar(dataOut);
      
      // The file will be automatically closed when the NcFile object goes
      // out of scope. This frees up any internal netCDF resources
      // associated with the file, and flushes any buffers.
      
      //cout << "*** SUCCESS writing example file simple_xy.nc!" << endl;
      return 0; 
    }
  catch(NcException& e)
    {e.what();
      return NC_ERR;
    }
}
 
int main()
{
    int ret;
    if(ret = create_file("simple_xy_nc4.nc", NcFile::nc4))
    return ret;
    cout << "*** SUCCESS creating nc4 file" << endl;
 
    if(ret = create_file("simple_xy_nc4classic.nc", NcFile::nc4classic))
    return ret;
    cout << "*** SUCCESS creating nc4classic file" << endl;
 
    if(ret = create_file("simple_xy_classic.nc", NcFile::classic))
    return ret;
    cout << "*** SUCCESS creating classic file" << endl;
 
    if(ret = create_file("simple_xy_classic64.nc", NcFile::classic64))
    return ret;
    cout << "*** SUCCESS creating classic64 file" << endl;
 
    return 0;
}