wppaste
WordPress

tag_exists( int|string $tag_name ): mixed

Since
2.3.0
Source
wp-admin/includes/taxonomy.php:222
Checks whether a post tag with a given name exists.

Compatibility

WordPress
since 2.3.0
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

$tag_nameint|string

Return value

mixed
Returns null if the term does not exist.
Returns an array of the term ID and the term taxonomy ID if the pairing exists.
Returns 0 if term ID 0 is passed to the function.

Performance profile

How much work a call to tag_exists() 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
Heavy

Reaches the database via get_terms().

Scaling
Constant

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

Instructions
6

Executed per call on PHP 8.5. The body compiles to 6.

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 tag_exists()
  • querycontent queryget_terms()one call below tag_exists()

Further down the call graph this can also reach option, cache, serialize 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 · 1 distinct outcome

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

WhenInstructionsCalls it makes
always6term_exists()

Across PHP versions

Compiles the same on PHP 7.4, 8.1, 8.2, 8.3, 8.4, 8.5 and 8.6-dev: 6 instructions, 6 executed per call, 0 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 · 1

Source code

View on Trac View on GitHub 

function tag_exists( $tag_name ) {	return term_exists( $tag_name, 'post_tag' );}

Changelog

Introduced in 2.3.0. 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-admin/includes/taxonomy.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it.
Corrections
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