I need to pass a value from PHP to C++. I think I can do with PHP's passthru() function.
Then I want C++ to do something to that value and return the result to PHP.
This is the bit I can't work out, does anyone know how to pass data from C++ to PHP?
I'd rather not use an intermediate file as I am thinking this will slow things down.
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4 Answers
You could have your c++ app send its output to stdout, then call it from PHP with backticks, e.g.
$output=`myapp $myinputparams`;
1 Comment
Columbo
Thank you very much to all answer-ers, I expect I will need to graduate to the more flexible solutions in time but for now this has worked. Thanks.
wow thanks a lot to Columbo & Paul Dixon.
Now I can run php to call c++ thn pass back value to php~ =)
Here I provide a sample cpp & php for it:
A simple program for adding up inputs:
a.cpp (a.exe):
#include<iostream>
#include<cstdlib>
using namespace std;
int main(int argc, char* argv[]) {
int val[2];
for(int i = 1; i < argc; i++) { // retrieve the value from php
val[i-1] = atoi(argv[i]);
}
int total = val[0] + val[1]; // sum up
cout << total; // std::cout will output to php
return 0;
}
sample.php:
<?php
$a = 2;
$b = 3;
$c_output=`a.exe $a $b`; // pass in the two value to the c++ prog
echo "<pre>$c_output</pre>"; //received the sum
echo "Output: " . ($output + 1); //modify the value in php and output
?>
output:
5
Output: 6
Comments
If you need to communicate to a running C++ program, a socket connection over the localhost might be the simplest, most platform-independent and most widely supported solution for communicating between the two processes. Sockets were traditionally built to communicate over network interfaces, but I have seen them used in many cases as a method of doing a pipe. They are fairly ubiquitous and supported in most modern languages.
Here's a C guide for socket programming. for your C++ program.
Comments
This article about wrapping C++ classes in a PHP extension may help.
EDIT: all the solutions in other answers are far simpler, but less flexible. It all depends on what you need.
4 Comments
Doug T.
I would say if anything a socket connection is more flexible, you can send binary data anywhere to do anything :) Your solution may be better in another sense in that it integrates php and c++ code which may or may not be more what the OP is asking.
Jacob B
On the other hand, you still need to serialize/deserialize any data you want to send, which IMO qualifies as less flexible. The advantage of using a language's extension interface is that you get to handle the language's data structures directly--for sockets you "only" get strings of bytes.
Columbo
Out of these three methods which in your opinios would be the quickest. To me it appears that the backticks method has to start and execute the C++ script whereas the sockets and (I think) wrapper methods rely on C++ programs that are memory resident and so can respond quicker. Does that seem reasonable or have I got it wrong?
Jacob B
Yes, that's correct. Wrapper script is faster than sockets by a little tiny bit--there's some extra overhead due to serialization and memory allocation. Backticks have to not only start the C++ script but also, I believe, invoke the shell.