Find all possible 2 letter combinations in a given string, using PHP [duplicate]

Answer 1

If you want to use substr

function str2array($string) {
    $strArray = [];
    for ($i = 0; $i < strlen($string); $i++) {
        $strArray[] = substr($string, $i, 1);
    }
    return $strArray;
}

But use str_split instead.

$string = 'tone';
$strArray = str_split($string);

foreach ($strArray as $key => $char1) {
    $strArray2 = $strArray;
    unset($strArray2[$key]);
    foreach ($strArray2 as $char2) {
        $permutations[] = $char1 . $char2;
    }
}
//EDIT: adding array_unique in case of dupes
$uniquePermutations=array_unique($permutations);
print_r($uniquePermutations);

Array ( [0] => to [1] => tn [2] => te [3] => ot [4] => on [5] => oe [6] => nt [7] => no [8] => ne [9] => et [10] => eo [11] => en )