[netCDF #ZDR-128646]: Ncfile for cpp

Camilla,

> I have built netcdf on cygwin. However, there are still some errors. Would
> you please help me to have a look whether the errors are from installation
> or my script?
> 
> In cygwin, I typed 'g++ test.cpp'
> The log file is called 'log.test1'

You have to also tell g++ where to look for the netcdf_c++ library and the 
netcdf library that it calls.  For example, if they were both installed in
the directory "/usr/local/lib", and if the include files netcdfcpp.h and
netcdf.h were installed in "/usr/local/include" you would need to use 
something like

  g++ -I/usr/local/include test.cpp -L/usr/local/lib -lnetcdf_c++ -lnetcdf

Also, I think you'll need to allocate space for the file name you want to
store in "f", rather than just declaring it to be a "char *" pointer that's
unitialized.  So, it would be better to use something like

  #define MAX_PATH_LENGTH 100
  char f[MAX_PATH_LENGTH];

or use the appropriate const for your operating system, instead of just

  char *f;

--Russ

> --------------------------------------------------
> From: "Unidata netCDF Support" <address@hidden>
> Sent: Wednesday, September 01, 2010 10:33 AM
> To: <address@hidden>
> Cc: <address@hidden>
> Subject: [netCDF #ZDR-128646]: Ncfile for cpp
> 
> >> Thank you for your reply.
> >> The problem is solved. However, a new error occurred which is called
> >> 'linker
> >> error'.
> >> I think this maybe because of the improper installation of my NETCDF.
> >> Actually, I built netcdf on win32 and using DEV-C++ to edit and compile
> >> cpp
> >> program.
> >> I downloaded the precompiled win32 netcdf file. And now I think, for cpp,
> >> I
> >> have to build it myself again. However, I dunno how to build it my own.
> >> Therefore, I would be grateful whether you can send me a copy of
> >> precompiled
> >> netcdf or teach me how to build it my own.
> >
> > The current status of the netCDF port to Windows is summarized in these
> > two FAQ
> > entries for netCDF version 4 and version 4.1:
> >
> >  http://www.unidata.ucar.edu/netcdf/docs/faq.html#windows_netcdf4
> >  http://www.unidata.ucar.edu/netcdf/docs/faq.html#windows_netcdf4_1
> >
> > In short, building netCDF on Windows is not easy, and the easiest way to
> > do it
> > currently is with the Cygwin development environment, because with cygwin,
> > you
> > can follow the same steps as for building netCDF on Unix.  The link below
> > tells you
> > about building with cygwin, and also how to get prebuilt DLLs for earlier
> > versions of
> > netCDF, which are probably all you need if you want to read or write
> > netCDF classic
> > format files:
> >
> >
> > http://www.unidata.ucar.edu/netcdf/docs/netcdf-install/Building-on-Windows.html#Building-on-Windows
> >
> > --Russ
> >
> >> --------------------------------------------------
> >> From: "Unidata netCDF Support" <address@hidden>
> >> Sent: Wednesday, September 01, 2010 6:18 AM
> >> To: <address@hidden>
> >> Cc: <address@hidden>
> >> Subject: [netCDF #ZDR-128646]: Ncfile for cpp
> >>
> >> > Hi Camilla,
> >> >
> >> >> I am writing a C++ program to read the data in a netcdf file. In the
> >> >> script, I use 'Ncfile' to read the .nc file. However, the compiler
> >> >> said
> >> >> that the function 'Ncfile' was not found. Would you please give me
> >> >> some
> >> >> advice?
> >> >>
> >> >> ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
> >> >>
> >> >> using namespace std;
> >> >> #include <iostream>        // This is a key C++ library
> >> >> #include "netcdfcpp.h"
> >> >>
> >> >> string dir ("G:/result/");
> >> >> string code ("us0000");
> >> >> const string path = dir + code;
> >> >> const string fil = path + "/" + "wrfout_" + code + ".nc";
> >> >>
> >> >> int main ()
> >> >> {
> >> >> NcFile file(fil, NcFile::ReadOnly);
> >> >> if ( !file->is_valid() ) {
> >> >> delete fil;
> >> >> exit(1);
> >> >> }
> >> >> NcVar* var = fil->get_var("P");
> >> >> if(var)
> >> >> printf("variable's name is %s/n", var->name());
> >> >> system("pause");
> >> >> return 0;
> >> >> }
> >> >
> >> > Yes, the netCDF C++ library was developed in the mid-1990's and is
> >> > showing its age (no use of Exceptions, Templates, or namespaces, for
> >> > example).  The netCDF Java API is much more up-to-date.  An
> >> > experimental
> >> > new C++ API for netCDF-4, contributed by Lynton Appel, is available in
> >> > the 4.1.1 release and is built if you configure with --enable-cxx4, but
> >> > it still needs a little more work to support netCDF classic files.
> >> >
> >> > The current C++ API is just a thin wrapper layer on top of the C
> >> > library, so in particular, it takes C char* arguments instead of C++
> >> > string arguments where character strings are required.  So if you
> >> > change
> >> > all the string declarations to the corresponding char* or char[]
> >> > declarations, things should work:
> >> >
> >> > using namespace std;
> >> > #include <iostream>        // This is a key C++ library
> >> > #include "netcdfcpp.h"
> >> > #include <strings.h>
> >> >
> >> > char dir[] = "G:/result/";
> >> > char code[] = "us0000";
> >> > const char *path = strcat(dir, code);
> >> > char fil[NC_MAX_NAME];
> >> >
> >> > int main ()
> >> > {
> >> >   sprintf(fil, "%s/wrfout_%s.nc", path, code);
> >> >   NcFile file(fil, NcFile::ReadOnly);
> >> >   if ( !file.is_valid() ) {
> >> >        delete fil;
> >> >        exit(1);
> >> >        }
> >> >        NcVar* var = file.get_var("P");
> >> >        if(var)
> >> >        printf("variable's name is %s/n", var->name());
> >> >   system("pause");
> >> >   return 0;
> >> > }
> >> >
> >> > --Russ
> >> >
> >> >
> >> > Russ Rew                                         UCAR Unidata Program
> >> > address@hidden                      http://www.unidata.ucar.edu
> >> >
> >> >
> >> >
> >> > Ticket Details
> >> > ===================
> >> > Ticket ID: ZDR-128646
> >> > Department: Support netCDF
> >> > Priority: Normal
> >> > Status: Closed
> >> >
> >> >
> >>
> >>
> >
> > Russ Rew                                         UCAR Unidata Program
> > address@hidden                      http://www.unidata.ucar.edu
> >
> >
> >
> > Ticket Details
> > ===================
> > Ticket ID: ZDR-128646
> > Department: Support netCDF
> > Priority: Normal
> > Status: Closed
> >
> >
> 

Russ Rew                                         UCAR Unidata Program
address@hidden                      http://www.unidata.ucar.edu



Ticket Details
===================
Ticket ID: ZDR-128646
Department: Support netCDF
Priority: Normal
Status: Closed