Change Read More Text for Excerpts on WordPress

post.php

<?php
function wpcode_snippets_change_read_more( $read_more, $read_more_text ) {

	// Edit the line below to add your own "Read More" text.
	$custom_text = 'Read the whole post';

	$read_more = str_replace( $read_more_text, $custom_text, $read_more );

	return $read_more;
}

add_filter( 'the_content_more_link', 'wpcode_snippets_change_read_more', 15, 2 );