wp_check_invalid_utf8( string $text, bool $strip = false ): string
- Since
- 2.8.0, 6.9.0
- Source
wp-includes/formatting.php:1127
Description
Note! This function only performs its work if the blog_charset is set to UTF-8. For all other values it returns the input text unchanged.
Note! Unless requested, this returns an empty string if the input contains any sequences of invalid UTF-8. To replace invalid byte sequences, pass true as the optional $strip parameter.
Consider using wp_scrub_utf8() instead which does not depend on the value of blog_charset.
Example:
// The blog_charset is latin1, so this returns the input unchanged.
$every_possible_input === wp_check_invalid_utf8( $every_possible_input );
// Valid strings come through unchanged.
'test' === wp_check_invalid_utf8( 'test' );
$invalid = "the byte xC0 is never allowed in a UTF-8 string.";
// Invalid strings are rejected outright.
'' === wp_check_invalid_utf8( $invalid );
// “Stripping” invalid sequences produces the replacement character instead.
"the byte \u{FFFD} is never allowed in a UTF-8 string." === wp_check_invalid_utf8( $invalid, true );
'the byte � is never allowed in a UTF-8 string.' === wp_check_invalid_utf8( $invalid, true );Compatibility
- WordPress
- since 6.9.0
- 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
$textstring- String which is expected to be encoded as UTF-8 unless
blog_charsetis another encoding. $stripbooloptional- Whether to replace invalid sequences of bytes with the Unicode replacement character (U+FFFD
�). Defaultfalsereturns an empty string for invalid UTF-8 inputs.Default:false
Return value
string- The checked text.
Performance profile
How much work a call to wp_check_invalid_utf8() does, and what it touches: the algorithmic scaling, the Zend instruction count per call across PHP versions, the hooks it hands control to, and the core code that calls it. Measured from the compiled opcodes, not a stopwatch, so every number is identical on any machine running the same PHP version, and every function in core is ranked by cost.
- Cost class
- Moderate
- Scaling
- Constant
- Instructions
- 8–23
- Plugin surface
- None
- Called by
- 6
Reads stored settings via get_option(), cached per request but not free on a cold cache.
No loop in the body: the same number of instructions runs whatever you pass in.
Executed per call on PHP 8.5, depending on the branch taken. The body compiles to 26.
Nothing here hands control to plugin code.
6 places in core call this, so the cost is paid more often than your own code shows.
What it touches
- optionoption read or write
get_option()one call below wp_check_invalid_utf8()
Further down the call graph this can also reach hook, cache, serialize, query and transient. Those are the worst case, several calls deep and usually down an error path, not what a normal call pays.
What one call costs · 6 distinct outcomes
One number would be a lie: the work depends on which branch runs. These are every distinct cost wp_check_invalid_utf8() can have, taken from its control-flow graph on PHP 8.5.
| When | Instructions | Calls it makes |
|---|---|---|
| always | 8–12 | none |
!isset($is_utf8) | 15 | is_utf8_charset() |
isset($is_utf8) | 16–17 | wp_is_valid_utf8() |
!isset($is_utf8) | 19–20 | is_utf8_charset(), wp_is_valid_utf8() |
isset($is_utf8) && !wp_is_valid_utf8() | 20 | wp_is_valid_utf8(), wp_scrub_utf8() |
!isset($is_utf8) && !wp_is_valid_utf8() | 23 | is_utf8_charset(), wp_is_valid_utf8(), wp_scrub_utf8() |
Across PHP versions
Compiles the same on PHP 7.4, 8.1, 8.2, 8.3, 8.4, 8.5 and 8.6-dev: 26 instructions, 8–23 executed per call, 5 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 · 3
- is_utf8_charset()Indicates if a given slug for a character set represents the UTF-8 text encoding. If not provided, examines the current blog's charset.
- wp_is_valid_utf8()Determines if a given byte string represents a valid UTF-8 encoding.
- wp_scrub_utf8()Replaces ill-formed UTF-8 byte sequences with the Unicode Replacement Character.
Used by · 6
- _sanitize_text_fields()Internal helper function to sanitize a string from user input or from the database.
- _wp_json_convert_string()Converts a string to UTF-8, so that it can be safely encoded to JSON.
- esc_attr()Escaping for HTML attributes.
- esc_html()Escaping for HTML blocks.
- esc_js()Escapes single quotes, `"`, ``, `&`, and fixes line endings.
- esc_xml()Escaping for XML blocks.
Source code
function wp_check_invalid_utf8( $text, $strip = false ) { $text = (string) $text; if ( 0 === strlen( $text ) ) { return ''; } // Store the site charset as a static to avoid multiple calls to get_option(). static $is_utf8 = null; if ( ! isset( $is_utf8 ) ) { $is_utf8 = is_utf8_charset(); } if ( ! $is_utf8 || wp_is_valid_utf8( $text ) ) { return $text; } return $strip ? wp_scrub_utf8( $text ) : '';}Changelog
Introduced in 2.8.0. Unchanged from 6.7.7 through 7.1.0.
Signature, return type and hooks compared across 5 parsed releases.
About this page
- Parsed data
- Generated from the wordpress-develop 7.0.4 tag, from
src/wp-includes/formatting.php, and regenerated for each WordPress release so it tracks the code rather than a snapshot of it. - Corrections
- Something wrong on this page? Report it and it gets fixed in the next regeneration.