ArrayAccess::offsetExists

(PHP 5, PHP 7, PHP 8)

ArrayAccess::offsetExistsWhether an offset exists

Description

public ArrayAccess::offsetExists(mixed $offset): bool

Whether or not an offset exists.

This method is executed when using isset() or empty() on objects implementing ArrayAccess.

Note:

When using empty() ArrayAccess::offsetGet() will be called and checked if empty only if ArrayAccess::offsetExists() returns true.

Parameters

offset

An offset to check for.

Return Values

Returns true on success or false on failure.

Note:

The return value will be casted to bool if non-boolean was returned.

Examples

Example #1 ArrayAccess::offsetExists() example

<?php
class obj implements arrayaccess {
    public function 
offsetSet($offset$value): void {
        
var_dump(__METHOD__);
    }
    public function 
offsetExists($var): bool {
        
var_dump(__METHOD__);
        if (
$var == "foobar") {
            return 
true;
        }
        return 
false;
    }
    public function 
offsetUnset($var): void {
        
var_dump(__METHOD__);
    }
    
#[\ReturnTypeWillChange]
    
public function offsetGet($var) {
        
var_dump(__METHOD__);
        return 
"value";
    }
}

$obj = new obj;

echo 
"Runs obj::offsetExists()\n";
var_dump(isset($obj["foobar"]));

echo 
"\nRuns obj::offsetExists() and obj::offsetGet()\n";
var_dump(empty($obj["foobar"]));

echo 
"\nRuns obj::offsetExists(), *not* obj:offsetGet() as there is nothing to get\n";
var_dump(empty($obj["foobaz"]));
?>

The above example will output something similar to:

Runs obj::offsetExists()
string(17) "obj::offsetExists"
bool(true)

Runs obj::offsetExists() and obj::offsetGet()
string(17) "obj::offsetExists"
string(14) "obj::offsetGet"
bool(false)

Runs obj::offsetExists(), *not* obj:offsetGet() as there is nothing to get
string(17) "obj::offsetExists"
bool(true)

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