import java.util.*;

public class PermutationExample {
    public static void main(String args[]) throws Exception {
        Scanner input = new Scanner(System.in);
        System.out.print("Enter String: ");
        String chars = input.next();
        showPattern("", chars);
    }

    public static void showPattern(String st, String chars) {
        if (chars.length() <= 1)
            System.out.println(st + chars);
        else
            for (int i = 0; i < chars.length(); i++) {
                try {
                    String newString = chars.substring(0, i)
                            + chars.substring(i + 1);
                    showPattern(st + chars.charAt(i), newString);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
    }
}

function permute($str,$i,$n) {
   if ($i == $n)
       print "$str\n";
   else {
        for ($j = $i; $j < $n; $j++) {
          swap($str,$i,$j);
          permute($str, $i+1, $n);
          swap($str,$i,$j);
       }
   }
}

function swap(&$str,$i,$j) {
    $temp = $str[$i];
    $str[$i] = $str[$j];
    $str[$j] = $temp;
}   

$str = "hey";
permute($str,0,strlen($str));

$string = "ABC";  
$strings = explode(' ', $string);

print_r(concat($strings, ""));

function concat(array $array, $base_string) {

    $results = array();
    $count = count($array);
    $b = 0;
    foreach ($array as $key => $elem){
        $new_string = $base_string . " " . $elem;
        $results[] = $new_string;
        $new_array = $array;

        unset($new_array[$key]);

        $results = array_merge($results, concat ($new_array, $new_string));

    }
    return $results;
}

function permute($str,$i,$n) {
   if ($i == $n)
       print "$str\n";
   else {
        for ($j = $i; $j < $n; $j++) {
          swap($str,$i,$j);
          permute($str, $i+1, $n);
          swap($str,$i,$j);
       }
   }
}

function swap(&$str,$i,$j) {
    $temp = $str[$i];
    $str[$i] = $str[$j];
    $str[$j] = $temp;
}   

$str = "hey";
permute($str,0,strlen($str));

this helps me but there is problem

when i type string hey it generates only this result

(hey hye ehy eyh yeh yhe)

but i want in this way

y

e

h

ye

he

ey

eh

eyh

yeh

hey

i mean all possible worlds that i can make from the given alphabets

these generated words must contain

all single abphabets

all combibation two alphabets

and all combination from three alphabets

i want this script in php

thank