Convert php array to formatted string

In your code, you need to write

$b .= $this->_replace_amp($value); // note the period

Without the period, you are initiating $b every time your script finds a new array, but you want to append the results to $b.

Other than that, there is a nice implode function for multidimensional arrays available:

/**
 * Recursively implodes an array with optional key inclusion
 * 
 * Example of $include_keys output: key, value, key, value, key, value
 * 
 * @access  public
 * @param   array   $array         multi-dimensional array to recursively implode
 * @param   string  $glue          value that glues elements together   
 * @param   bool    $include_keys  include keys before their values
 * @param   bool    $trim_all      trim ALL whitespace from string
 * @return  string  imploded array
 */ 
function recursive_implode(array $array, $glue = ',', $include_keys = false, $trim_all = true)
{
    $glued_string = '';

    // Recursively iterates array and adds key/value to glued string
    array_walk_recursive($array, function($value, $key) use ($glue, $include_keys, &$glued_string)
    {
        $include_keys and $glued_string .= $key.$glue;
        $glued_string .= $value.$glue;
    });

    // Removes last $glue from string
    strlen($glue) > 0 and $glued_string = substr($glued_string, 0, -strlen($glue));

    // Trim ALL whitespace
    $trim_all and $glued_string = preg_replace("/(\s)/ixsm", '', $glued_string);

    return (string) $glued_string;
}

Source: https://gist.github.com/jimmygle/2564610

I think either json_encode( your_php_array ) or serialize() function is help you.

You want to use function implode(). No need to re-invent the wheel.

<?php

$arr = ['one', 'two', 'three'];

echo implode(',', $arr); // one, two, three

$b = $this->_replace_amp($value); change in this line to $b .= $this->_replace_amp($value); this answer as per your coding

[ 
 { "value": "rigging" }, 
 { "value": "animation" }, 
 { "value": "modeling" }
]


function _replace_amp($post = array()) {
    foreach($post as $key => $value)
    {
        if (is_array($value)) {
           $b .= $this->_replace_amp($value);
        }  else  {
            $b .= $value . ', ';
        }
    }

    return $b;
}

batter way to do this using used implode(',',$array);