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Collator::compare -- collator_compareCompare two Unicode strings


Object-oriented style

public Collator::compare(string $string1, string $string2): int|false

Procedural style

collator_compare(Collator $object, string $string1, string $string2): int|false

Compare two Unicode strings according to collation rules.



Collator object.


The first string to compare.


The second string to compare.

Return Values

Return comparison result:

  • 1 if string1 is greater than string2 ;

  • 0 if string1 is equal to string2;

  • -1 if string1 is less than string2 .

Returns false on failure.


This function may return Boolean false, but may also return a non-Boolean value which evaluates to false. Please read the section on Booleans for more information. Use the === operator for testing the return value of this function.


Example #1 collator_compare() example

$s2 'hello';

$coll collator_create'en_US' );
$res  collator_compare$coll$s1$s2 );

if (
$res === false) {
collator_get_error_message$coll );
} else if( 
$res ) {
"s1 is greater than s2\n";
} else if( 
$res ) {
"s1 is less than s2\n";
} else {
"s1 is equal to s2\n";

The above example will output:

s1 is greater than s2

Example #2 Comparing strings without diacritics or case-sensitivity

= new Collator'en' );
$c->setStrengthCollator::PRIMARY );

if ( 
$c->compare'Séan''Sean' ) == )
"The same\n";

The above example will output:

The same

This example instructs the collator to compare with only taking the base characters into account. The documentation for Collator->setStrength() explains the different strengths.

See Also

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User Contributed Notes 1 note

erik at eldata dot se
1 year ago
The Collator class with method compare does what the non existing mb_strcmp, mb_strcasecmp, mb_strnatcmp and mb_strnatcasecmp would do for multibyte strings (UTF8) - but better! :-)

For "case": the Collator is case insensitive due to Collator::CASE_FIRST defaults to Collator::OFF, but can be changed with method setAttribute.

For "nat" (natural sort order for numbers): use method setAttribute with Collator::NUMERIC_COLLATION and Collator:ON to enable.
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