Getting environment variable from script

Run.sh

#! /bin/bash

export RUN_FROM_SCRIPT=1

./a.out

test.cpp

#include <iostream>
#include <cstdlib>
#include <cstring>

#include <opencv2/opencv.hpp>

int main()
{
    char* runFromScriptVar = getenv("RUN_FROM_SCRIPT");
    if(runFromScriptVar)
    {
        std::cout << "OK" << std::endl;
    }
    else
    {
        system("zenity --error --text=\"Please launch from script\"");
    }
}