Unable to call custom function in Laravel

Question

I'm trying to retrieve permutation set based on a string. However, i couldn't execute the function properly. I'm not really good with public static, or private or how should I call the function.

<?php namespace Helpers;

class Helper {

public static function permute($str,$i,$n) 
{
   if ($i == $n)
       return "$str\n";
   else {
        for ($j = $i; $j < $n; $j++) {
          swap($str,$i,$j);
          permute($str, $i+1, $n);
          swap($str,$i,$j); // backtrack.
       }
   }
}

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

This is how I call the function from my controller.

Helper::permute($str,0,strlen($str))

I'm getting this error:

Call to undefined function Helpers\swap()

padarom · Accepted Answer · 2015-04-22 09:13:21Z

3

You're calling the method swap() and permute() from a static context, but handle them as if they were non-static.
Try changing it to the following:

public static function permute($str,$i,$n) 
{
    if ($i == $n)
        return "$str\n";
    else {
        for ($j = $i; $j < $n; $j++) {
            self::swap($str,$i,$j);
            self::permute($str, $i+1, $n);
            self::swap($str,$i,$j); // backtrack.
        }
    }
}

edited Apr 22, 2015 at 9:13

answered Apr 22, 2015 at 9:07

padarom

3,6795 gold badges36 silver badges58 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

1myb Over a year ago

Changed the method of call for 3 lines into self:: but wonder why it's not returning any value.

Collectives™ on Stack Overflow

Unable to call custom function in Laravel

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related