Included C++ libraries are not working when executing C++ from PHP

Question

I am trying to run C++ on an XAMPP server using the exec() function in PHP. I am importing a C++ json library . When I run the C++ code from terminal it works perfectly, but when I run it in PHP I get no output. As soon as I add any code from the json library, I no longer get any output.

PHP:

<?php
  exec("./cPlusPlus", $output);
  echo $output;
?>

C++ compiled with g++ -std=c++11:

#include <iostream>
#include <vector>
#include <string>
#include <cstdlib>
#include <json>

using namespace std;
using json = nlohmann::json;

int main(int argc, char *argsv[])
{
  // If I remove this line, then I get the correct output
  // If I keep this line, I get no output
  json data = {"json stuff"};

  cout << "This is returned to PHP.";

  return 0;
}

It seems like the problem has to do with the fact that I am using a library. Do I need to do something special in order to run libraries with the PHP exec() function?

Answer 1

I fixed my problem with the help of @ChristianHackl. I changed exec("./cPlusPlus", $output); to exec("./cPlusPlus 2>&1", $output); in order to see the thrown errors. I was then able to see the error:

libstdc++.so.6: version `GLIBCXX_3.4.14' not found

and found the solution here .