php中的proc_open+fwrite应用有关问题

php中的proc_open+fwrite应用问题
我想在php用proc_open调用一个c++写的exe程序，由于里面有要求输入参数所以我用fwrite写入终端，php代码如下

PHP code

<?php $descriptorspec = array(
   0 => array("pipe", "r"),  // stdin is a pipe that the child will read from
   1 => array("pipe", "w"),  // stdout is a pipe that the child will write to
   2 => array("file", "error-output.txt", "a") // stderr is a file to write to
);

$process = proc_open("d:\\64test.exe", $descriptorspec, $pipes);

if (is_resource($process)) {
    // $pipes now looks like this:
    // 0 => writeable handle connected to child stdin
    // 1 => readable handle connected to child stdout
    // Any error output will be appended to /tmp/error-output.txt
    
    fwrite($pipes[0], "q");
    fclose($pipes[0]);
    while (!feof($pipes[1])) 
    {
        $result = fgets($pipes[1], 1024);
        echo "r:$result
";
    }
    fclose($pipes[1]);
    
    // It is important that you close any pipes before calling
    // proc_close in order to avoid a deadlock
    $return_value = proc_close  ($process);

    echo "command returned $return_value
";
}
?>

C/C++ code

#include 
using namespace std;
int main(int argc,char *argv[])
{
    char buf[1024]={0};
    /*fgets(buf,sizeof(buf),stdin);*/
    while(buf[0]!='q')
    {
        std::cin>>buf;
        std::cout