Giving the application some data on launch

Question

I'm trying to create an application that can receive some data on launch from another program. For example:

Start_App.exe calls Main_App.exe and gives it the current date, all at the same time
(while launching it)

Main_App.exe outputs the date on its console

Without the data passed by Start_App the other program can't work correctly or will do something else. I've been searching for a while but it seems like I'm missing the technical names...

Answer 1

You'll probably want to use command-line arguments.
They are passed by writing them out, separated by spaces, directly after the program name.

Like so:

#include <iostream>

int main(int argc, char *argv[])
{
    using namespace std;

    cout << "There are " << argc << " arguments:" << endl;

    // Loop through each argument and print its number and value
    for (int nArg=0; nArg < argc; nArg++)
        cout << nArg << " " << argv[nArg] << endl;

    return 0;
}

argc is the number of arguments the program received.
*argv[] is an array of strings, one for each argument.

If you call the program like this:

Program.exe arg1 arg2 arg3

It gives you:

There are 3 arguments:
0 arg1
1 arg2
2 arg3