wppaste
WordPress

in_category( int|string|int[]|string[] $category, int|null|WP_Post $post = null ): bool

Since
1.2.0, 2.7.0
Source
wp-includes/category-template.php:257
Checks if the current post is within any of the given categories.

Description

The given categories are checked against the post's categories' term_ids, names and slugs.
Categories given as integers will only be checked against the post's categories' term_ids.

Prior to v2.5 of WordPress, category names were not supported.
Prior to v2.7, category slugs were not supported.
Prior to v2.7, only one category could be compared: in_category( $single_category ).
Prior to v2.7, this function could only be used in the WordPress Loop.
As of 2.7, the function can be used anywhere if it is provided a post ID or post object.

For more information on this and similar theme functions, check out the https://developer.wordpress.org/themes/basics/conditional-tags/ Conditional Tags article in the Theme Developer Handbook.

Compatibility

WordPress
since 2.7.0
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

$categoryint|string|int[]|string[]
Category ID, name, slug, or array of such to check against.
$postint|null|WP_Postoptional
Post to check. Defaults to the current post.Default: null

Return value

bool
True if the current post is in any of the given categories.

Performance profile

How much work a call to in_category() 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
Trivial

Touches nothing outside its own arguments.

Scaling
Constant

No loop in the body: the same number of instructions runs whatever you pass in.

Instructions
5–9

Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 10.

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 one call costs · 2 distinct outcomes

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

WhenInstructionsCalls it makes
empty($category)5none
!empty($category)9has_category()

Across PHP versions

Compiles the same on PHP 7.4, 8.1, 8.2, 8.3, 8.4, 8.5 and 8.6-dev: 10 instructions, 5–9 executed per call, 1 branch. 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 · 1

Source code

View on Trac View on GitHub 

function in_category( $category, $post = null ) {	if ( empty( $category ) ) {		return false;	} 	return has_category( $category, $post );}

Changelog

Introduced in 1.2.0. One change between 6.7.7 and 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.

6.9.7
Parameter $post retyped from int|WP_Post to int|null|WP_Post.verified against source
2.7.0
The $post parameter was added.from the docblock
1.2.0
Introduced.from the docblock

About this page

Parsed data
Generated from the wordpress-develop 7.1.0 tag, from src/wp-includes/category-template.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.
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