This is a Multilingual Wordpress functions to detect a language by pretty URLs like..`domain.com/en/``domain.com/postname/en/``domain.com/pagetname/en/`Add this code in your `functions.php`After added code go to `wp-admin/options-permalink.php` press `Save Changes`So you can use`<?php echo lang();?>``<?php if( lang() === "en" ) ?>`In your theme...

functions.php

<?php
function lang_support() {
    return array('en','fr'); // Add your support lang-code (1st place is a default)
}

function rewrite_lang(){
    $langs = lang_support();
    foreach($langs as $lang) {
        add_rewrite_endpoint($lang,EP_PERMALINK|EP_PAGES|EP_ROOT|EP_CATEGORIES);
    }
}
add_action('init','rewrite_lang');

function lang(){
    global $wp_query;
    $langs = lang_support();
    $lang_r = "";
    foreach($langs as $lang) {
        if(isset($wp_query->query_vars[$lang])) {
            $lang_r = $lang;
            $_SESSION['lang'] = $lang_r;
        }
    }
    if(in_array($lang_r,$langs)) {
        return $lang_r;
    } else {
        return $langs[0];
    }
}

function init_session(){session_start();}
add_action('init','init_session',1);

function lang_session() { // Redirect by JS if session is set
    $url_lang= basename($_SERVER['REQUEST_URI']);
    if(!in_array($url_lang,lang_support()) && isset($_SESSION['lang'])) {
        if(!is_404()) {
          wp_redirect(currentURL().$_SESSION['lang'],301);
          exit;
        }
    }
}
add_action('wp_head','lang_session');

function output_buffer() {ob_start();}
add_action('init','output_buffer');

function currentURL() {
    $pageURL=(@$_SERVER["HTTPS"]=="on")?"https://":"http://";
        if($_SERVER["SERVER_PORT"]!="80"){
            $pageURL.=$_SERVER["SERVER_NAME"].":".$_SERVER["SERVER_PORT"].$_SERVER["REQUEST_URI"];
        }else{
            $pageURL.=$_SERVER["SERVER_NAME"].$_SERVER["REQUEST_URI"];
        }
        return $pageURL;
}