What potential issues can arise when using array_merge to combine arrays with different key names in PHP?

When using array_merge to combine arrays with different key names in PHP, potential issues can arise if the keys are not unique. If the arrays being merged have keys with the same name, the values from the second array will overwrite the values from the first array. To avoid this issue, you can use the + operator to merge the arrays, which will only add elements from the second array that do not already exist in the first array. 

$array1 = ['key1' => 'value1', 'key2' => 'value2'];
$array2 = ['key2' => 'new_value', 'key3' => 'value3'];

$mergedArray = $array1 + $array2;

print_r($mergedArray);

Keywords

array_merge PHP key names associative arrays data loss

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