define("CLIENT_ID", "PUT_YOUR_CONSUMER_KEY_HERE");
define("CLIENT_SECRET", "PUT_YOUR_CONSUMER_SECRET_HERE");
define("LOGIN_URI", "<a target="_blank" href="https://login.salesforce.com" rel="nofollow">https://login.salesforce.com</a>");

define("USERNAME", "user@example.com");
define("PASSWORD", "password");

function salesforce_login($username, $password) {
    $params = "grant_type=password&client_id=".CLIENT_ID.
            "&client_secret=".CLIENT_SECRET.
            "&username=$username&password=$password";
    
    $token_url = LOGIN_URI . "/services/oauth2/token";
    
    $curl = curl_init($token_url);
    curl_setopt($curl, CURLOPT_HEADER, false);
    curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($curl, CURLOPT_POST, true);
    curl_setopt($curl, CURLOPT_POSTFIELDS, $params);
    $json_response = curl_exec($curl);
    $status = curl_getinfo($curl, CURLINFO_HTTP_CODE);
    if ( $status != 200 ) {
        die("Error: call to URL $token_url failed with status $status");
    }
    
    return json_decode($json_response, true);
}

$response = salesforce_login(USERNAME, PASSWORD);
$access_token = $response["access_token"];
$instance_url = $response["instance_url"];
//call method show accounts


show_accounts($instance_url, $access_token);


//show accounts defined
function show_accounts($instance_url, $access_token) {
    $query = "SELECT Name, Id from Account LIMIT 100";
    $url = "$instance_url/services/data/v41.0/query?q=" . urlencode($query);

    $curl = curl_init($url);
    curl_setopt($curl, CURLOPT_HEADER, false);
    curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
    curl_setopt($curl, CURLOPT_HTTPHEADER,
            array("Authorization: OAuth $access_token"));

    $json_response = curl_exec($curl);
    curl_close($curl);

    $response = json_decode($json_response, true);

    $total_size = $response['totalSize'];

    echo "$total_size record(s) returned<br/><br/>";
    foreach ((array) $response['records'] as $record) {
        echo $record['Id'] . ", " . $record['Email'] . "<br/>";
    }
    echo "<br/>";
}