Question

I want to pass a value of an input variable in my program lets say#1 to another program #2 and i want #2 to print the data it got to screen, both are needed to be written in c++. The this will be on Linux.

Answer 1

In response to your comment to Roopesh Majeti’s answer, here’s a very simple example using environment variables:

First program:

// p1.cpp - set the variable
#include <cstdlib>
using namespace std;;    
int main() {
    _putenv( "MYVAR=foobar" );
    system( "p2.exe" );
}

Second program:

// p2.cpp - read the variable
#include <cstdlib>
#include <iostream>
using namespace std;;

int main() {
    char * p = getenv( "MYVAR" );
    if ( p == 0 ) {
        cout << "Not set" << endl;
    }
    else {
        cout << "Value: " << p << endl;
    }
}

Note:

• there is no standard way of setting an environment variable
• you will need to construct the name=value string from the variable contents