Generate dots between characters with all possibilities

Question

I am looking for an algorithm in PHP to make output of all possibilities with dot. produces we can put do in any place of word but repeated two dots after each other is now

Answer 1

Recursive way:

Put current char of source in the result string
if current char is the last one
     output result
else
     call recursive function with the next char index
     add dot to result and call recursive function with the next char index

Iterative way:

There are 2^(Len-1) combinations with dots, where Len i word length. Make a loop for k = 0..2^(Len-1) - 1 and for every k insert dots in those places, where binary representation of k contains 1s (k=2 = binary 010 = > po.le)

Answer 2

I found the solution eventually by helpful guidance of https://stackoverflow.com/users/844416/mbo:

function stringInsert($str,$insertstr,$pos){
    $str = substr($str, 0, $pos) . $insertstr . substr($str, $pos);
    return $str;
}

function generate($var="note",$i=0){
    $length = strlen($var);

    while ($i+1 < $length) {
        $i++;
        $new = stringInsert($var,'.',$i);
        echo $new;
        generate($new,$i+1);

    }
}


generate('shaghayegh');

for example for keyword "note" generated 7 strings

for keyword "shaghayegh" generated 511 strings