Here’s a handy function that takes the category name and returns the category id:
function get_category_id($name) {
$term = get_term_by('name', $name, 'category');
return $term->term_id;
}
Save this function to functions.php
and call it like any other function. In this example we use it to return a list of all posts in a category named “Services”:
$posts = get_posts(array(
'category' => get_category_id('Services')
));