WordPress at a glance
function is not described

WP_Theme::get_template_directory() public WP 3.4.0

Returns the absolute path to the directory of a theme's "template" files.

In the case of a child theme, this is the absolute path to the directory of the parent theme's files.

{} It's a method of the class: WP_Theme{}

No Hooks.

Return

String. Absolute path of the template directory.

Usage

$WP_Theme = new WP_Theme();
$WP_Theme->get_template_directory();

Changelog

Since 3.4.0 Introduced.

Code of WP_Theme::get_template_directory() WP 5.5.1

<?php
public function get_template_directory() {
	if ( $this->parent() ) {
		$theme_root = $this->parent()->theme_root;
	} else {
		$theme_root = $this->theme_root;
	}

	return $theme_root . '/' . $this->template;
}