在php中重复运行外部程序

Question

I want to run a program written with c++ in web server repetitive. Because there is something that php can't do, but c++ can do it easy.

I searched and found that it could be done by using exec function in php.

I used this in js setInterval to run that program every 100ms. But it seems that that program runs when web page loads and in js code, I have the same output.

for example, when I want to get current date from c++ program. the cpp code is:

#include <iostream>
#include <ctime>
using namespace std;
int main()
{
    time_t now = time(0);
    tm *ltm = localtime(&now);
    cout << 1 + ltm->tm_sec;
    return 0;
}

and in index.php file I used this for print current second at page every 100ms.

<script>
    setInterval(function(){
        var date = "<?php passthru("print_date.exe"); ?>";
        document.write(date + "<br>");
    },100);
</script>

but it prints always the same!

Is there any other way to do this? Thanks!

Answer 1

Because php code is executed only 1 time. Use Ajax as an option.

//updated next day. 1. file (index.php)

<script>
var aj;

setInterval(function()
{
aj = new XMLHttpRequest();
aj.open('GET',"/print_date.php",false);
aj.onreadystatechange  = processData;
aj.send(null);
},1000);

function processData()
{
var date = '';
if (aj.readyState == 4) 
{
date = aj.responseText;
document.write(date + "<br>")   
}
}
</script>

It is very simple synchronous ajax. interval is 1000, not 100, because 1000ms = 1s (C++ program returns time in seconds!).

2) So, print_date.php is

<?php 
 error_reporting(0); //because any warning destroys output for ajax
 passthru("print_date.exe");