Re: Running a script file inside c++ code

[sumeet kumar]

HI Tatsuro,

I don't think its useful for me. 

Anyway, what I currently have, I can show you.

I made a OctPaser class.

-- OctParser.h

#ifndef OCTPARSER_H
#define OCTPARSER_H

#include <string>

using namespace::std;

class OctParser{

    public:

        OctParser();
        ~OctParser();

        string eval(const string& command);
        void exit();

    private:

};

#endif //OCTPARSER_H

--OctParser.cpp

#include <octave/oct.h>
#include <octave/octave.h>
#include <octave/parse.h>
#include <octave/toplev.h>
#include <octave/ov.h>
#include "OctParser.h"

#include <iostream>
#include <fstream>
#include <string>

using namespace::std;

/******************************************************************************
****************************** Constructor ************************************
******************************************************************************/

OctParser::OctParser(){
    char *oct_argv[3] = {(char*)"embeded",(char*)"-q",(char*)"--interactive"};
    octave_main(3,oct_argv,true);
}

OctParser::~OctParser(){
}

/******************************************************************************
**************************** Public Functions *********************************
******************************************************************************/

string OctParser::eval(const string& function) {

    int status = 0;
    ofstream ScriptFile("script", ios::out);
    ScriptFile << function ;
    ScriptFile.close();
    source_file("script");
    //eval_string(function,false,status);
    octave_value f = eval_string("num2str(ans,10);",false,status);
    string val = f.string_value();
    return val;
}

void OctParser::exit(){

    clean_up_and_exit (1);
    // reset();
}

Now let say, I have to compute the following " x=1; y=5;z= x+y; sin(z)". Now what I do is write in a string and then write in a"script"  file using and then evaluate it [look at the function] . An example is shown below.

main.cpp

OctParser Evaluate = OctParser();

string function = " x=1; y=5; x+y"

string result =Evaluate.eval(function);

result

result = 0.07845

This, all works well. The only problem is that I need to generate a "script" file each time I do any of these computations. Because the Source_File() function requires a file_name as parameter.

Now, what I want is the following.

1. I do not want to generate any file and then pass on the octave parser. This is very slow and takes lot of time.
2. I want a function that do not need to generate any external file. i.e I would like a function such as 

• FUNCTION(string) -> directly giving me result
• Also, in the string I should be able to use any function of octave or from any external file, which I am currently able to use through my approach as shown above.

Thanks

On Sat, Aug 13, 2016 at 2:59 PM, address@hidden <address@hidden> wrote:

--- sumeet.kumar507 wrote:
> Hello all,
>
> I am using octave parser to evaluate _expression_ inside my c++ code. The expressions can be very simple can can also be complicated  depending upon the user.
>
> 1)So basically, I have a string which contains all the commands that needs to be executed by octave. But I am unable to execute and get the results of the string containing commands.
>
> 2)So, I found another way, in which I write the string in an file and then parse it using octave as
>
>     char *oct_argv[3] = {(char*)"embeded",(char*)"-q",(char*)"--interactive"};
>     octave_main(3,oct_argv,true);
>     ofstream ScriptFile("script", ios::out);
>     ScriptFile << function ;
>     ScriptFile.close();
>     source_file("script");
>
> where function is the string that needs to be evaluated.
>
> The second approach works but the problem is very slow because of generation of file each time I want a computation. I usually end up in thousands/millions of them and it gets extremely slow, like taking days.. to complete.
>
>
> In order to be more efficient, i want to do it as 1st way. So anybody has any idea, how to do it more faster/effecient or how to do as in first way.
>
> Sumeet
>
> --
>          
> Sumeet Kumar SinhaGraduate Student
> Phone: (+1) 5306018271
> Website : http://www.sumeetsinha.in/

https://www.gnu.org/software/octave/doc/interpreter/Standalone-Programs.html#Standalone-Programs

Is the second example useful for you?

Other method is to commucate with octave via pipe.

HTH

Tatsuro

--

         

Sumeet Kumar Sinha

Graduate Student

Phone: (+1) 5306018271

Website : http://www.sumeetksinha.com/