Title: wp-includes/functions.php | Page 6 of 10 | Developer.WordPress.org --- # File: wp-includes/functions.php * function[wp_debug_backtrace_summary()](https://developer.wordpress.org/reference/functions/wp_debug_backtrace_summary/) * Returns a comma-separated string or array of functions that have been called to get to the current point in code. * Used by [1 function](https://developer.wordpress.org/reference/functions/wp_debug_backtrace_summary/#used-by) | Uses [1 function](https://developer.wordpress.org/reference/functions/wp_debug_backtrace_summary/#uses) | Source: [wp-includes/functions.php:7369](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L7369-L7409) * function[_get_non_cached_ids()](https://developer.wordpress.org/reference/functions/_get_non_cached_ids/) * Retrieves IDs that are not already present in the cache. * Used by [6 functions](https://developer.wordpress.org/reference/functions/_get_non_cached_ids/#used-by) | Uses [1 function](https://developer.wordpress.org/reference/functions/_get_non_cached_ids/#uses) | Source: [wp-includes/functions.php:7421](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L7421-L7439) * function[_device_can_upload()](https://developer.wordpress.org/reference/functions/_device_can_upload/) * Tests if the current device has the capability to upload files. * Used by [3 functions](https://developer.wordpress.org/reference/functions/_device_can_upload/#used-by) | Uses [1 function](https://developer.wordpress.org/reference/functions/_device_can_upload/#uses) | Source: [wp-includes/functions.php:7477](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L7477-L7491) * hook[extra_{$context}_headers](https://developer.wordpress.org/reference/hooks/extra_context_headers/) * Filters extra file headers by context. * Used by [1 function](https://developer.wordpress.org/reference/hooks/extra_context_headers/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/hooks/extra_context_headers/#uses) | Source: [wp-includes/functions.php:7057](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L7057-L7057) * function[__return_true()](https://developer.wordpress.org/reference/functions/__return_true/) * Returns true. * Used by [0 functions](https://developer.wordpress.org/reference/functions/__return_true/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/functions/__return_true/#uses) | Source: [wp-includes/functions.php:7087](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L7087-L7089) * function[__return_false()](https://developer.wordpress.org/reference/functions/__return_false/) * Returns false. * Used by [0 functions](https://developer.wordpress.org/reference/functions/__return_false/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/functions/__return_false/#uses) | Source: [wp-includes/functions.php:7102](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L7102-L7104) * function[force_ssl_admin()](https://developer.wordpress.org/reference/functions/force_ssl_admin/) * Determines whether to force SSL used for the Administration Screens. * Used by [5 functions](https://developer.wordpress.org/reference/functions/force_ssl_admin/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/functions/force_ssl_admin/#uses) | Source: [wp-includes/functions.php:6418](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L6418-L6428) * function[__return_zero()](https://developer.wordpress.org/reference/functions/__return_zero/) * Returns 0. * Used by [0 functions](https://developer.wordpress.org/reference/functions/__return_zero/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/functions/__return_zero/#uses) | Source: [wp-includes/functions.php:7115](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L7115-L7117) * function[wp_guess_url()](https://developer.wordpress.org/reference/functions/wp_guess_url/) * Guesses the URL for the site. * Used by [5 functions](https://developer.wordpress.org/reference/functions/wp_guess_url/#used-by) | Uses [1 function](https://developer.wordpress.org/reference/functions/wp_guess_url/#uses) | Source: [wp-includes/functions.php:6440](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L6440-L6477) * function[wp_suspend_cache_addition()](https://developer.wordpress.org/reference/functions/wp_suspend_cache_addition/) * Temporarily suspends cache additions. * Used by [3 functions](https://developer.wordpress.org/reference/functions/wp_suspend_cache_addition/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/functions/wp_suspend_cache_addition/#uses) | Source: [wp-includes/functions.php:6495](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L6495-L6503) * function[wp_suspend_cache_invalidation()](https://developer.wordpress.org/reference/functions/wp_suspend_cache_invalidation/) * Suspends cache invalidation. * Used by [0 functions](https://developer.wordpress.org/reference/functions/wp_suspend_cache_invalidation/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/functions/wp_suspend_cache_invalidation/#uses) | Source: [wp-includes/functions.php:6519](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L6519-L6525) * function[is_main_site()](https://developer.wordpress.org/reference/functions/is_main_site/) * Determines whether a site is the main site of the current network. * Used by [18 functions](https://developer.wordpress.org/reference/functions/is_main_site/#used-by) | Uses [3 functions](https://developer.wordpress.org/reference/functions/is_main_site/#uses) | Source: [wp-includes/functions.php:6539](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L6539-L6551) * function[is_main_network()](https://developer.wordpress.org/reference/functions/is_main_network/) * Determines whether a network is the main network of the Multisite installation. * Used by [4 functions](https://developer.wordpress.org/reference/functions/is_main_network/#used-by) | Uses [3 functions](https://developer.wordpress.org/reference/functions/is_main_network/#uses) | Source: [wp-includes/functions.php:6583](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L6583-L6595) * hook[global_terms_enabled](https://developer.wordpress.org/reference/hooks/global_terms_enabled/) * Filters whether global terms are enabled. * Used by [0 functions](https://developer.wordpress.org/reference/hooks/global_terms_enabled/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/hooks/global_terms_enabled/#uses) | Source: [wp-includes/functions.php:6239](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L6239-L6239) * function[wp_timezone_override_offset()](https://developer.wordpress.org/reference/functions/wp_timezone_override_offset/) * Modifies gmt_offset for smart timezone handling. * Used by [0 functions](https://developer.wordpress.org/reference/functions/wp_timezone_override_offset/#used-by) | Uses [1 function](https://developer.wordpress.org/reference/functions/wp_timezone_override_offset/#uses) | Source: [wp-includes/functions.php:6677](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L6677-L6690) * function[_wp_timezone_choice_usort_callback()](https://developer.wordpress.org/reference/functions/_wp_timezone_choice_usort_callback/) * Sort-helper for timezones. * Used by [0 functions](https://developer.wordpress.org/reference/functions/_wp_timezone_choice_usort_callback/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/functions/_wp_timezone_choice_usort_callback/#uses) | Source: [wp-includes/functions.php:6702](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L6702-L6747) * function[wp_timezone_choice()](https://developer.wordpress.org/reference/functions/wp_timezone_choice/) * Gives a nicely-formatted list of timezone strings. * Used by [0 functions](https://developer.wordpress.org/reference/functions/wp_timezone_choice/#used-by) | Uses [8 functions](https://developer.wordpress.org/reference/functions/wp_timezone_choice/#uses) | Source: [wp-includes/functions.php:6759](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L6759-L6947) * function[_cleanup_header_comment()](https://developer.wordpress.org/reference/functions/_cleanup_header_comment/) * Strips close comment and close php tags from file headers used by WP. * Used by [2 functions](https://developer.wordpress.org/reference/functions/_cleanup_header_comment/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/functions/_cleanup_header_comment/#uses) | Source: [wp-includes/functions.php:6960](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L6960-L6962) * function[wp_scheduled_delete()](https://developer.wordpress.org/reference/functions/wp_scheduled_delete/) * Permanently deletes comments or posts of any type that have held a status of ‘ trash’ for the number of days defined in EMPTY_TRASH_DAYS. * Used by [0 functions](https://developer.wordpress.org/reference/functions/wp_scheduled_delete/#used-by) | Uses [8 functions](https://developer.wordpress.org/reference/functions/wp_scheduled_delete/#uses) | Source: [wp-includes/functions.php:6974](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L6974-L7014) * function[get_file_data()](https://developer.wordpress.org/reference/functions/get_file_data/) * Retrieves metadata from a file. * Used by [6 functions](https://developer.wordpress.org/reference/functions/get_file_data/#used-by) | Uses [2 functions](https://developer.wordpress.org/reference/functions/get_file_data/#uses) | Source: [wp-includes/functions.php:7036](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L7036-L7074) * function[iis7_supports_permalinks()](https://developer.wordpress.org/reference/functions/iis7_supports_permalinks/) * Checks if IIS 7+ supports pretty permalinks. * Used by [4 functions](https://developer.wordpress.org/reference/functions/iis7_supports_permalinks/#used-by) | Uses [1 function](https://developer.wordpress.org/reference/functions/iis7_supports_permalinks/#uses) | Source: [wp-includes/functions.php:6330](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L6330-L6355) * hook[iis7_supports_permalinks](https://developer.wordpress.org/reference/hooks/iis7_supports_permalinks/) * Filters whether IIS 7+ supports pretty permalinks. * Used by [1 function](https://developer.wordpress.org/reference/hooks/iis7_supports_permalinks/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/hooks/iis7_supports_permalinks/#uses) | Source: [wp-includes/functions.php:6354](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L6354-L6354) * function[_deprecated_function()](https://developer.wordpress.org/reference/functions/_deprecated_function/) * Marks a function as deprecated and inform when it has been used. * Used by [425 functions](https://developer.wordpress.org/reference/functions/_deprecated_function/#used-by) | Uses [4 functions](https://developer.wordpress.org/reference/functions/_deprecated_function/#uses) | Source: [wp-includes/functions.php:5643](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L5643-L5700) * function[validate_file()](https://developer.wordpress.org/reference/functions/validate_file/) * Validates a file name and path against an allowed set of rules. * Used by [14 functions](https://developer.wordpress.org/reference/functions/validate_file/#used-by) | Uses [1 function](https://developer.wordpress.org/reference/functions/validate_file/#uses) | Source: [wp-includes/functions.php:6372](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L6372-L6408) * hook[deprecated_function_run](https://developer.wordpress.org/reference/hooks/deprecated_function_run/) * Fires when a deprecated function is called. * Used by [1 function](https://developer.wordpress.org/reference/hooks/deprecated_function_run/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/hooks/deprecated_function_run/#uses) | Source: [wp-includes/functions.php:5654](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L5654-L5654) * hook[deprecated_function_trigger_error](https://developer.wordpress.org/reference/hooks/deprecated_function_trigger_error/) * Filters whether to trigger an error for deprecated functions. * Used by [1 function](https://developer.wordpress.org/reference/hooks/deprecated_function_trigger_error/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/hooks/deprecated_function_trigger_error/#uses) | Source: [wp-includes/functions.php:5663](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L5663-L5663) * function[_deprecated_file()](https://developer.wordpress.org/reference/functions/_deprecated_file/) * Marks a file as deprecated and inform when it has been used. * Used by [1 function](https://developer.wordpress.org/reference/functions/_deprecated_file/#used-by) | Uses [4 functions](https://developer.wordpress.org/reference/functions/_deprecated_file/#uses) | Source: [wp-includes/functions.php:5885](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L5885-L5945) * hook[deprecated_file_included](https://developer.wordpress.org/reference/hooks/deprecated_file_included/) * Fires when a deprecated file is called. * Used by [1 function](https://developer.wordpress.org/reference/hooks/deprecated_file_included/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/hooks/deprecated_file_included/#uses) | Source: [wp-includes/functions.php:5897](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L5897-L5897) * hook[deprecated_file_trigger_error](https://developer.wordpress.org/reference/hooks/deprecated_file_trigger_error/) * Filters whether to trigger an error for deprecated files. * Used by [1 function](https://developer.wordpress.org/reference/hooks/deprecated_file_trigger_error/#used-by) | Uses [0 functions](https://developer.wordpress.org/reference/hooks/deprecated_file_trigger_error/#uses) | Source: [wp-includes/functions.php:5906](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L5906-L5906) * function[_deprecated_argument()](https://developer.wordpress.org/reference/functions/_deprecated_argument/) * Marks a function argument as deprecated and inform when it has been used. * Used by [64 functions](https://developer.wordpress.org/reference/functions/_deprecated_argument/#used-by) | Uses [4 functions](https://developer.wordpress.org/reference/functions/_deprecated_argument/#uses) | Source: [wp-includes/functions.php:5973](https://github.com/WordPress/wordpress-develop/blob/7.1/src/wp-includes/functions.php#L5973-L6030) [Previous 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