Answers for "wp code for get category id by slug"

wp get category by id

<?php
$category_id = 21; //use your own category id
$category = get_category( $category_id );
echo $category->name;
echo $category->cat_ID;
//print_r($category);
//to get all the properties of the $category
?>

wp get post id by slug

url_to_postid( site_url('the_slug') );