is_utf8_charset( string|null $blog_charset = null ): bool

Description

true === is_utf8_charset( 'UTF-8' );
true === is_utf8_charset( 'utf8' );
false === is_utf8_charset( 'latin1' );
false === is_utf8_charset( 'UTF 8' );

// Only strings match.
false === is_utf8_charset( [ 'charset' => 'utf-8' ] );

// Without a given charset, it depends on the site option "blog_charset".
$is_utf8 = is_utf8_charset();

Compatibility

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

Parameters

$blog_charsetstring|nulloptional

Slug representing a text character encoding, or "charset".
E.g. "UTF-8", "Windows-1252", "ISO-8859-1", "SJIS".
Default value is to infer from "blog_charset" option.Default: null

Return value

bool

Whether the slug represents the UTF-8 encoding.

Performance profile

How much work a call to is_utf8_charset() 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

Moderate

Reads stored settings via get_option(), cached per request but not free on a cold cache.

Scaling

Constant

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

Instructions

6–10

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

3

3 places in core call this, so the cost is paid more often than your own code shows.

What it touches

• optionoption read or writeget_option()called directly
• hookthird-party callbacksapply_filters()one call below is_utf8_charset()
• cacheobject cachewp_cache_get()one call below is_utf8_charset()
• serializeserialisationmaybe_unserialize()one call below is_utf8_charset()

Further down the call graph this can also reach 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 is_utf8_charset() can have, taken from its control-flow graph on PHP 8.5.

Uses · 2

• _is_utf8_charset()Indicates if a given slug for a character set represents the UTF-8 text encoding.
• get_option()Retrieves an option value based on an option name.

Used by · 3

• WP_Script_Modules::print_script_module_data()Print data associated with Script Modules.
• _canonical_charset()Retrieves a canonical form of the provided charset appropriate for passing to PHP functions such as htmlspecialchars() and charset HTML attributes.
• wp_check_invalid_utf8()Checks for invalid UTF8 in a string.

Source code

View on Trac ↗View on GitHub ↗

7715function is_utf8_charset( $blog_charset = null ) {7716	return _is_utf8_charset( $blog_charset ?? get_option( 'blog_charset' ) );7717}

Changelog

Introduced in 6.6.0. 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

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