Let us understand this code?

[spring2014]

Hi all,
My teacher gave me a code and told me to try to understand it.
I have some questions would you please help me?

1- I know this code is for modelling but why he has written this part of code?

2- what are lines 20-23 for?
3-what does line 27 do? What is necessity of it?
4- what do lines 30-38 do?
5-what doe lines 42-43 do? what does tk:: do?
6- what is the purpose of lines 47-51-55-59?

  #include <iostream>
#include <fstream>
#include <math.h>
#include <cstdlib>
#include <sys/time.h>
#include <time.h>
#include "omp.h"


using namespace std;

//--------------------------------------------------------------------------
// global variables
double ds=0.25, dt=1, t=50000;
double scale_factor;
int nx, ny;
const int nq=9, nd=2;
const int np=5000;

#include "function1.h"
#include "function2.h"
#include "time_keeping.h"
#include "output.h"

//--------------------------------------------------------------------------
// main program
int main(int argc, char *argv[]){

//--------------------------------------------------------------------------
// initiate simulation

	function1_initiate(argc, argv);

	function2_initiate();

	output_initiate();

	time_initiate(argc, argv);

//--------------------------------------------------------------------------
// set program running
	tk::running=true;
	while(tk::running){

//--------------------------------------------------------------------------
// write output to file
		write_output();

//--------------------------------------------------------------------------
// 
		function1_method();

//--------------------------------------------------------------------------
// 
		function2_model();

//--------------------------------------------------------------------------
// increase time step and check if end time is reached
		time_increase();

//--------------------------------------------------------------------------
// end of main loop
	}

//--------------------------------------------------------------------------
// end program
	return 0;
}

[hellox]

2- what are lines 20-23 for?

Files that are created by yourself.

3-what does line 27 do? What is necessity of it?

Every program needs a main function, it is the function that is read first by compiler.
Your program consists of what is inside the Main ()


while(tk::running){ , runs while "tk::running" is true.
meaning: "tk::running" > 0.

Someone please correct me if im wrong about any of the above.

[spring2014]

Thanks for your reply.
1- But what does "int argc, char *argv[])" in main statement do?
2- what would happen if did not write "tk::" in line 42?
3- what about lines 31-38? what do argc, argv do?

[hellox]

The first argument to main() is the number of
parameters passed to the program.


The second argument to main() is an
array of pointers to null-terminated character strings

2- what would happen if did not write "tk::" in line 42?

I don't know since i don't know what's inside the files that are included.
But since tk::running is set to true the while loop on next line is infinite.
if you didn't set tk::running to true on line 42, the loop would just run aslong tk::running is true. or >= 1