WordPress: Checks if paramater(s) are in the post type

example.php

<?php

/**
 * Example One: String
 */
 if( is_post_type( 'post_type01' ) ):
  
  echo "This is the post type";
  
endif;
 
/**
 * Example Two: Array
 */

if( is_post_type( array( 'post_type01', 'post_type02', 'post_type03', 'post_type04', 'post_type05' ) ) ):
  
  echo "This is one of the post types supplied";
  
endif;

functions.php

<?php

// ...

/**
 * Checks if paramater(s) are in the post type
 *
 * @param    int/string/array   $post_types   Post type name(s) or id
 * @return   boolean                          if in post type
 * @version  1.0.0
 * @since    1.0.0
 */
if ( ! function_exists( 'is_post_type' ) ) :

  function is_post_type( $post_types = null ) {
    // If our variable is not set stop as soon as possible
    if( ! isset( $post_types ) ) {
      return false;
    }

    $array = array();
    if( $post_types == get_post_type() ){
      array_push( $array, $post_type );
      return true;
    }

    foreach ( $post_types as $value ) {

      if( $value == get_post_type() ){
        array_push( $array, $value );
        return true;
      }

    }
  

    return false;
  }

endif;

// ...