Title: wp-includes/functions.php | Page 5 of 10 | Developer.WordPress.org --- # File: wp-includes/functions.php * function[_deprecated_constructor()](https://developer.wordpress.org/reference/functions/_deprecated_constructor/) * Marks a constructor as deprecated and informs when it has been used. * Used by [9 functions](https://developer.wordpress.org/reference/functions/_deprecated_constructor/#used-by) | Uses [4 functions](https://developer.wordpress.org/reference/functions/_deprecated_constructor/#uses) | Source: [wp-includes/functions.php:5722](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L5722-L5786) * hook[deprecated_constructor_run](https://developer.wordpress.org/reference/hooks/deprecated_constructor_run/) * Fires when a deprecated constructor is called. * Used by [1 function](https://developer.wordpress.org/reference/hooks/deprecated_constructor_run/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/hooks/deprecated_constructor_run/#uses) | Source: [wp-includes/functions.php:5734](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L5734-L5734) * hook[deprecated_constructor_trigger_error](https://developer.wordpress.org/reference/hooks/deprecated_constructor_trigger_error/) * Filters whether to trigger an error for deprecated functions. * Used by [1 function](https://developer.wordpress.org/reference/hooks/deprecated_constructor_trigger_error/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/hooks/deprecated_constructor_trigger_error/#uses) | Source: [wp-includes/functions.php:5745](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L5745-L5745) * hook[wp_delete_file](https://developer.wordpress.org/reference/hooks/wp_delete_file/) * Filters the path of the file to delete. * Used by [1 function](https://developer.wordpress.org/reference/hooks/wp_delete_file/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/hooks/wp_delete_file/#uses) | Source: [wp-includes/functions.php:7858](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L7858-L7858) * function[wp_delete_file()](https://developer.wordpress.org/reference/functions/wp_delete_file/) * Deletes a file. * Used by [10 functions](https://developer.wordpress.org/reference/functions/wp_delete_file/#used-by) | Uses [1 function](https://developer.wordpress.org/reference/functions/wp_delete_file/#uses) | Source: [wp-includes/functions.php:7850](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L7850-L7865) * function[wp_json_encode()](https://developer.wordpress.org/reference/functions/wp_json_encode/) * Encodes a variable into JSON, with some confidence checks. * Used by [103 functions](https://developer.wordpress.org/reference/functions/wp_json_encode/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/functions/wp_json_encode/#uses) | Source: [wp-includes/functions.php:4443](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L4443-L4458) * function[wp_validate_boolean()](https://developer.wordpress.org/reference/functions/wp_validate_boolean/) * Filters/validates a variable as a boolean. * Used by [5 functions](https://developer.wordpress.org/reference/functions/wp_validate_boolean/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/functions/wp_validate_boolean/#uses) | Source: [wp-includes/functions.php:7829](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L7829-L7839) * hook[admin_memory_limit](https://developer.wordpress.org/reference/hooks/admin_memory_limit/) * Filters the maximum memory limit available for administration screens. * Used by [1 function](https://developer.wordpress.org/reference/hooks/admin_memory_limit/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/hooks/admin_memory_limit/#uses) | Source: [wp-includes/functions.php:8007](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L8007-L8007) * hook[image_memory_limit](https://developer.wordpress.org/reference/hooks/image_memory_limit/) * Filters the memory limit allocated for image manipulation. * Used by [1 function](https://developer.wordpress.org/reference/hooks/image_memory_limit/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/hooks/image_memory_limit/#uses) | Source: [wp-includes/functions.php:8023](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L8023-L8023) * function[wp_auth_check()](https://developer.wordpress.org/reference/functions/wp_auth_check/) * Checks whether a user is still logged in, for the heartbeat. * Used by [0 functions](https://developer.wordpress.org/reference/functions/wp_auth_check/#used-by) | Uses [1 function](https://developer.wordpress.org/reference/functions/wp_auth_check/#uses) | Source: [wp-includes/functions.php:7657](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L7657-L7660) * function[get_tag_regex()](https://developer.wordpress.org/reference/functions/get_tag_regex/) * Returns RegEx body to liberally match an opening HTML tag. * Used by [0 functions](https://developer.wordpress.org/reference/functions/get_tag_regex/#used-by) | Uses [1 function](https://developer.wordpress.org/reference/functions/get_tag_regex/#uses) | Source: [wp-includes/functions.php:7678](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L7678-L7683) * function[_canonical_charset()](https://developer.wordpress.org/reference/functions/_canonical_charset/) * Retrieves a canonical form of the provided charset appropriate for passing to PHP functions such as htmlspecialchars() and charset HTML attributes. * Used by [2 functions](https://developer.wordpress.org/reference/functions/_canonical_charset/#used-by) | Uses [1 function](https://developer.wordpress.org/reference/functions/_canonical_charset/#uses) | Source: [wp-includes/functions.php:7731](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L7731-L7753) * function[mbstring_binary_safe_encoding()](https://developer.wordpress.org/reference/functions/mbstring_binary_safe_encoding/) * Sets the mbstring internal encoding to a binary safe encoding when func_overload is enabled. * Used by [13 functions](https://developer.wordpress.org/reference/functions/mbstring_binary_safe_encoding/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/functions/mbstring_binary_safe_encoding/#uses) | Source: [wp-includes/functions.php:7778](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L7778-L7806) * function[reset_mbstring_encoding()](https://developer.wordpress.org/reference/functions/reset_mbstring_encoding/) * Resets the mbstring internal encoding to a users previously set encoding. * Used by [12 functions](https://developer.wordpress.org/reference/functions/reset_mbstring_encoding/#used-by) | Uses [1 function](https://developer.wordpress.org/reference/functions/reset_mbstring_encoding/#uses) | Source: [wp-includes/functions.php:7815](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L7815-L7817) * function[wp_is_stream()](https://developer.wordpress.org/reference/functions/wp_is_stream/) * Tests if a given path is a stream URL * Used by [9 functions](https://developer.wordpress.org/reference/functions/wp_is_stream/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/functions/wp_is_stream/#uses) | Source: [wp-includes/functions.php:7501](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L7501-L7512) * function[wp_checkdate()](https://developer.wordpress.org/reference/functions/wp_checkdate/) * Tests if the supplied date is valid for the Gregorian calendar. * Used by [7 functions](https://developer.wordpress.org/reference/functions/wp_checkdate/#used-by) | Uses [1 function](https://developer.wordpress.org/reference/functions/wp_checkdate/#uses) | Source: [wp-includes/functions.php:7527](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L7527-L7542) * hook[wp_checkdate](https://developer.wordpress.org/reference/hooks/wp_checkdate/) * Filters whether the given date is valid for the Gregorian calendar. * Used by [1 function](https://developer.wordpress.org/reference/hooks/wp_checkdate/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/hooks/wp_checkdate/#uses) | Source: [wp-includes/functions.php:7541](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L7541-L7541) * function[wp_auth_check_load()](https://developer.wordpress.org/reference/functions/wp_auth_check_load/) * Loads the auth check for monitoring whether the user is still logged in. * Used by [0 functions](https://developer.wordpress.org/reference/functions/wp_auth_check_load/#used-by) | Uses [7 functions](https://developer.wordpress.org/reference/functions/wp_auth_check_load/#uses) | Source: [wp-includes/functions.php:7555](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L7555-L7586) * function[__return_empty_array()](https://developer.wordpress.org/reference/functions/__return_empty_array/) * Returns an empty array. * Used by [0 functions](https://developer.wordpress.org/reference/functions/__return_empty_array/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/functions/__return_empty_array/#uses) | Source: [wp-includes/functions.php:7128](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L7128-L7130) * hook[wp_auth_check_load](https://developer.wordpress.org/reference/hooks/wp_auth_check_load/) * Filters whether to load the authentication check. * Used by [1 function](https://developer.wordpress.org/reference/hooks/wp_auth_check_load/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/hooks/wp_auth_check_load/#uses) | Source: [wp-includes/functions.php:7579](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L7579-L7579) * function[__return_null()](https://developer.wordpress.org/reference/functions/__return_null/) * Returns null. * Used by [0 functions](https://developer.wordpress.org/reference/functions/__return_null/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/functions/__return_null/#uses) | Source: [wp-includes/functions.php:7141](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L7141-L7143) * function[wp_auth_check_html()](https://developer.wordpress.org/reference/functions/wp_auth_check_html/) * Outputs the HTML that shows the wp-login dialog when the user is no longer logged in. * Used by [0 functions](https://developer.wordpress.org/reference/functions/wp_auth_check_html/#used-by) | Uses [7 functions](https://developer.wordpress.org/reference/functions/wp_auth_check_html/#uses) | Source: [wp-includes/functions.php:7593](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L7593-L7642) * function[__return_empty_string()](https://developer.wordpress.org/reference/functions/__return_empty_string/) * Returns an empty string. * Used by [0 functions](https://developer.wordpress.org/reference/functions/__return_empty_string/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/functions/__return_empty_string/#uses) | Source: [wp-includes/functions.php:7156](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L7156-L7158) * hook[wp_auth_check_same_domain](https://developer.wordpress.org/reference/hooks/wp_auth_check_same_domain/) * Filters whether the authentication check originated at the same domain. * Used by [1 function](https://developer.wordpress.org/reference/hooks/wp_auth_check_same_domain/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/hooks/wp_auth_check_same_domain/#uses) | Source: [wp-includes/functions.php:7605](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L7605-L7605) * function[send_nosniff_header()](https://developer.wordpress.org/reference/functions/send_nosniff_header/) * Sends a HTTP header to disable content type sniffing in browsers which support it. * Used by [0 functions](https://developer.wordpress.org/reference/functions/send_nosniff_header/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/functions/send_nosniff_header/#uses) | Source: [wp-includes/functions.php:7168](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L7168-L7170) * function[wp_find_hierarchy_loop()](https://developer.wordpress.org/reference/functions/wp_find_hierarchy_loop/) * Finds hierarchy loops using a callback function that maps object IDs to parent IDs. * Used by [2 functions](https://developer.wordpress.org/reference/functions/wp_find_hierarchy_loop/#used-by) | Uses [1 function](https://developer.wordpress.org/reference/functions/wp_find_hierarchy_loop/#uses) | Source: [wp-includes/functions.php:7211](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L7211-L7220) * function[wp_find_hierarchy_loop_tortoise_hare()](https://developer.wordpress.org/reference/functions/wp_find_hierarchy_loop_tortoise_hare/) * Uses the “The Tortoise and the Hare” algorithm to detect loops. * Used by [1 function](https://developer.wordpress.org/reference/functions/wp_find_hierarchy_loop_tortoise_hare/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/functions/wp_find_hierarchy_loop_tortoise_hare/#uses) | Source: [wp-includes/functions.php:7242](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L7242-L7272) * function[send_frame_options_header()](https://developer.wordpress.org/reference/functions/send_frame_options_header/) * Sends a HTTP header to limit rendering of pages to same origin iframes. * Used by [0 functions](https://developer.wordpress.org/reference/functions/send_frame_options_header/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/functions/send_frame_options_header/#uses) | Source: [wp-includes/functions.php:7282](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L7282-L7287) * function[wp_allowed_protocols()](https://developer.wordpress.org/reference/functions/wp_allowed_protocols/) * Retrieves a list of protocols to allow in HTML attributes. * Used by [11 functions](https://developer.wordpress.org/reference/functions/wp_allowed_protocols/#used-by) | Uses [2 functions](https://developer.wordpress.org/reference/functions/wp_allowed_protocols/#uses) | Source: [wp-includes/functions.php:7331](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L7331-L7350) * hook[kses_allowed_protocols](https://developer.wordpress.org/reference/hooks/kses_allowed_protocols/) * Filters the list of protocols allowed in HTML attributes. * Used by [1 function](https://developer.wordpress.org/reference/hooks/kses_allowed_protocols/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/hooks/kses_allowed_protocols/#uses) | Source: [wp-includes/functions.php:7346](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L7346-L7346) [Previous Page](https://developer.wordpress.org/reference/files/wp-includes/functions.php/page/4/?output_format=md) [1](https://developer.wordpress.org/reference/files/wp-includes/functions.php/?output_format=md)… [3](https://developer.wordpress.org/reference/files/wp-includes/functions.php/page/3/?output_format=md) [4](https://developer.wordpress.org/reference/files/wp-includes/functions.php/page/4/?output_format=md) 5 [6](https://developer.wordpress.org/reference/files/wp-includes/functions.php/page/6/?output_format=md) [7](https://developer.wordpress.org/reference/files/wp-includes/functions.php/page/7/?output_format=md)… [10](https://developer.wordpress.org/reference/files/wp-includes/functions.php/page/10/?output_format=md) [Next 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