wppaste
WordPress

get_rss( string $url, int $num_items = 5 ): bool

Since
1.5.0
Source
wp-includes/rss.php:935
Display RSS items in HTML list items.

Description

You have to specify which HTML list you want, either ordered or unordered before using the function. You also have to specify how many items you wish to display. You can't display all of them like you can with wp_rss() function.

Compatibility

WordPress
since 1.5.0
PHP
7.4–8.6-dev
  • 6.7.7
  • 6.8.8
  • 6.9.7
  • 7.0.4
  • 7.1.0

Present in every tracked release (6.7.7 to 7.1.0), and compiles on PHP 7.4 through 8.6-dev.

Parameters

$urlstring
URL of feed to display. Will not auto sense feed URL.
$num_itemsintoptional
Number of items to display, default is all.Default: 5

Return value

bool
False on failure.

Performance profile

How much work a call to get_rss() does, and what it touches: the algorithmic scaling, the Zend instruction count per call across PHP versions, the hooks it hands control to, and the core code that calls it. Measured from the compiled opcodes, not a stopwatch, so every number is identical on any machine running the same PHP version, and every function in core is ranked by cost.

Cost class
Light

Touches nothing outside its own arguments.

Scaling
Scales with input

The body loops, so the work grows with what you pass in.

Instructions
8–21

Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 39.

Plugin surface
None

Nothing here hands control to plugin code.

Called by
0

Nothing in core calls this; the cost is only what you spend yourself.

What it touches

  • hookthird-party callbacksapply_filters()one call below get_rss()

Further down the call graph this can also reach http, option, cache, serialize, query and transient. Those are the worst case, several calls deep and usually down an error path, not what a normal call pays.

What one call costs · 2 distinct outcomes

One number would be a lie: the work depends on which branch runs. These are every distinct cost get_rss() can have, taken from its control-flow graph on PHP 8.5.

WhenInstructionsCalls it makes
always8fetch_rss()
always20–21fetch_rss(), array_slice()

Across PHP versions

Compiles the same on PHP 7.4, 8.1, 8.2, 8.3, 8.4, 8.5 and 8.6-dev: 39 instructions, 8–21 executed per call, 3 branches. The work does not change between versions.

An instruction is not a fixed amount of time, so a matching count is not necessarily the same speed; what it rules out is a difference in the work itself.

Uses · 2

Source code

View on Trac View on GitHub 

function get_rss ($url, $num_items = 5) { // Like get posts, but for RSS	$rss = fetch_rss($url);	if ( $rss ) {		$rss->items = array_slice($rss->items, 0, $num_items);		foreach ( (array) $rss->items as $item ) {			echo "<li>\n";			echo "<a href='$item[link]' title='$item[description]'>";			echo esc_html($item['title']);			echo "</a><br />\n";			echo "</li>\n";		}	} else {		return false;	}}

Changelog

Introduced in 1.5.0. Unchanged from 6.7.7 through 7.1.0.

  1. 6.7.7
  2. 6.8.8
  3. 6.9.7
  4. 7.0.4
  5. 7.1.0

Signature, return type and hooks compared across 5 parsed releases.

About this page

Parsed data
Generated from the wordpress-develop 6.8.8 tag, from src/wp-includes/rss.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.
Corrections
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