Call a C program from php and read program output

Question

Could some one explain me how to run a C program from a php script and store console output of the C program to a php variable?

My program prints an integer value on the console using C printf() function. I want to read this value and store it in a php variable.
I am using linux. I tried exec but it doesn't display the variable value once echoed to the page

This the code snippet I am using.

exec("Release/matchface image1.jpg image2.jpg", $output);
while( list(,$row) = each($output) ) {
  echo $row. "<br />";
} 

Answer 1

You'll want to use the shell_exec() function (quoting) :

Execute command via shell and return the complete output as a string

Which means something that will look like this :

$output = shell_exec('/path/to/your/program');

Or, you could use the backtick operator -- which would do exactly the same thing (quoting) :

PHP will attempt to execute the contents of the backticks as a shell command; the output will be returned

And, in code :

$output = `/path/to/your/program`;