steam_group_members.php

<?php 
//Turn off errors in production since they can potentially reveal request information.
//error_reporting(0);
//Uncomment before public

/* A Generic GET request with cURL
 * String $cURL - URL to request
 * return array    
 */
function ValveGET_cURL($cURL) {

    $request = curl_init( trim($cURL) );
    curl_setopt( $request, CURLOPT_RETURNTRANSFER, TRUE );
    curl_setopt( $request, CURLOPT_FOLLOWLOCATION, TRUE );
    curl_setopt( $request, CURLOPT_MAXREDIRS, 3);
    curl_setopt( $request, CURLOPT_AUTOREFERER, TRUE);
    curl_setopt( $request, CURLOPT_CONNECTTIMEOUT, 5);
    curl_setopt( $request, CURLOPT_TIMEOUT, 10);
    $result = curl_exec( $request );
    $info = curl_getinfo( $request );
    $error = curl_errno( $request );
    curl_close( $request );
    return array('data' => $result, 'info' => $info, 'error' => $error);
}

$groupid = "steamuniverse";
$API_KEY = "FILL THIS";


$group_URL = 'http://steamcommunity.com/groups/' . $groupid . '/memberslistxml/?xml=1';

$return_array = ValveGET_cURL($group_URL);
$return_data = $return_array['data'];
$return_info = $return_array['info'];
$return_error = $return_array['error'];

//handle cURL errors
if($return_error !== 0) {
    error_log("Steam Group Thingy returned with cURL Error: " . $return_error, 0);
    exit;
}

$http_code = $return_info['http_code'];
if($http_code !== 200) {
    //Server is probably down, give a generic message if you want
    echo "Steam API is down";
    exit;
} else {
    //Request was successfull
    $group_object = simplexml_load_string($return_data);
    $group_object_members = $group_object->members->steamID64;

    $steamids = array();

    foreach($group_object_members as $user) {
        $string = (string)$user;
        if(ctype_digit($string)) {
            $steamids[] = $string;
        }
    }

    //Turn the first 100 or less into a string for the request.
    $idcount = count($steamids);
    $x = ($idcount < 100) ? $idcount : 100;
    $giantlistofusers = "";
    for($i = 0; $i < $x; $i++) {

        $giantlistofusers .= $steamids[$i];
        if($i <= $x) {
            $giantlistofusers .= ',';    
        }
    }
    $request_URL2 = 'http://api.steampowered.com/ISteamUser/GetPlayerSummaries/v0002/?key=' . $API_KEY . '&steamids=' . urlencode($giantlistofusers) . '&format=xml';

    $player_return = ValveGET_cURL($request_URL2 );

    $player_data = $player_return['data'];
    $player_info = $player_return['info'];
    $player_error = $player_return['error'];

    //handle cURL errors
    if($player_error !== 0) {
        error_log("Steam Group Thingy returned with cURL Error: " . $player_error, 0);
        exit;
    }

    $http_code2 = $player_info['http_code'];
    if($http_code2 !== 200) {
        //Server is probably down, give a generic message if you want
        echo "Steam API is down";
        exit;
    } else {

        $player_object = simplexml_load_string($player_data);

        var_dump($player_object->players);
    }
}


?>