Question

Is it possible (and if so, how) to write a program in C++ that takes parameters, then run that program from another C++ program.

Ie: I can create a function that adds two numbers:

int add(int a,int b){return a+b;}

Is it possible to do the same thing, except instead of a function, a separate C++ .exe?

EDIT: Since a lot of people don’t understand my question, I’ll try to say exactly what I want to know how to do.

I want to have a program, lets call it “p1”.

I want that program to get two numbers from the user:

int x,y;
cin>>x;
cin>>y;

Now I want to create another program, that takes two numbers, and adds them, the same way a function would, except a seperate program.

Then I want to run the second program from the first program with the numbers it got from the user. Ie:

#include<iostream>
using namespace std;
int main()
{
     int x,y;
     cin>>x;
     cin>>y;
     add(x,y); //this is how I would call a function named "add".  I want to know how to do that with a separate program instead of just a separate function.
     return 0;
}

EDIT: I figured out how to use

(void)system("C:\\Program Files\\test.exe");

How would I use that to pass arguments, and how could I write a program that takes those arguments?

Answer 1

On most OSes, you can pass arguments in system() by space-seperating them:

system("someapp.exe 42 24");

This string, of course, can be built up by sprintf or std::ostringstream or what have you.

Then you just need to process your arguments in the other program:

int main(int argc, char **argv) {
  // important - make sure we have enough args
  if (argc != 3) { // first (zeroth) argument is always the program name, so 1+2 args is needed
    fprintf(stderr, "Wrong number of arguments\n");
    return EXIT_FAILURE;
  }
  int a = atoi(argv[1]);
  int b = atoi(argv[2]);
  // do stuff
}