header dosyasının en başına dosya yolu bulmak için
<?=get_template_directory_url()?>
kodu yazıyorum ama hata veriyor.
Hata Kodu:

[B]Fatal error[/B]: Uncaught Error: Call to undefined function get_template_directory_url() in 
D:\xampp\htdocs\wp\wp-content\themes\FiYAZILIM\header.php:1 Stack trace: #0 
D:\xampp\htdocs\wp\wp-includes\template.php(722): require_once() 
#1 
D:\xampp\htdocs\wp\wp-includes\template.php(671): load_template('D:\\xampp\\htdocs...', true) 
#2 
D:\xampp\htdocs\wp\wp-includes\general-template.php(41): locate_template(Array, true) 
#3 
D:\xampp\htdocs\wp\wp-content\themes\FiYAZILIM\index.php(3): get_header() 
#4 
D:\xampp\htdocs\wp\wp-includes\template-loader.php(98): include('D:\\xampp\\htdocs...') 
#5 
D:\xampp\htdocs\wp\wp-blog-header.php(19): require_once('D:\\xampp\\htdocs...') 
#6 
D:\xampp\htdocs\wp\index.php(17): require('D:\\xampp\\htdocs...') 
#7 
{main} thrown in [B]D:\xampp\htdocs\wp\wp-content\themes\FiYAZILIM\header.php[/B] on line [B]1[/B]