twitter_api_example.php

<?php
ini_set('display_errors', 1);
require_once('TwitterAPIExchange.php');

$settings = array(
    'oauth_access_token' => "xxx",
    'oauth_access_token_secret' => "xxx",
    'consumer_key' => "xxx",
    'consumer_secret' => "xxx"
);


$url = 'https://api.twitter.com/1.1/statuses/user_timeline.json';
$getfield = '?screen_name=username';
$requestMethod = 'GET';
$twitter = new TwitterAPIExchange($settings);

echo $twitter->setGetfield($getfield)
             ->buildOauth($url, $requestMethod)
             ->performRequest();