parsing arguments from python to c++ -

i wanted know how change values of arguments in c++/c program python. in program below use newton-raphson method compute roots of function. want change value of variable xn (for initial guess) value given in python interface. code simple trying bigger code need change values of variables , dont want compile code each time change values of these variables.

i can write input file in order avoid compiling code again want is
controlling code more, instance, stop program @ time step , change values of variables , continue execution. tell me if there straightforward way that?

regards.

#include <iostream>                                                                                                                using namespace std;                                                                                                                  double first_derivative(double x) {     double dummy; // parabolic function     dummy = 2.0 * x + 7.0;     return (dummy); }  double second_derivative(double x) {     double dummy; //parabolic function     dummy = 2.0 ;     return(dummy); }   int main ()                                                                                                                          {                                                                                                                                        double xn,fd,sd;     int i,n;                                                                                                                                 i=0;             xn=4.0 ;       cout << << "    " << xn << "\n" ;      for(i=0; i<10 ; i++) {         fd =  first_derivative(xn);         sd =  second_derivative(xn);         xn = xn - fd/sd ;         cout << << "    " << fd << "    " << sd << "     " << xn << "\n" ;     }     return 0; } 

if want act python it's best write in python.

you cannot "change numbers" of compiled program. can do, however, make program accept parameters change @ runtime. can in c++ command-line parameters, configuration files, or asking input. easier involving python.

if reason parts of code have in c++ , want python, can expose c++ routines library python. 1 popular approach swig. make functions you'd call python accept changeable parameters. python script call them.