how arguments are passed to codeigniter method - php

Question

I have a method in a codeigniter controller which is sometimes called through the url and sometimes called internally from another method of the controller. When I call it internally I pass an array of arguments. Simplified version of method:
(within a controller)
function get_details($args='') {
if (isset($args['first_name']))
{
$first_name = $args['first_name'];
}
else
{
$first_name = $this->uri->segment(3);
}
... do some other stuff ...
}
The method is either called as:
<domain>/<controller>/get_details/abcd/efgh
or from another function of the controller as:
$this->get_details(array('first_name'=>'abcd', 'last_name'=>'efgh'));
I was expecting that when the method was called through the url, isset($args['first_name']) would be false, however it seems that called in this way the argument is there. I tried printing a couple of things and this is what I got:
print_r($args) ----> abcd
echo($args['first_name']) ----> a
echo($args['whatever_index_I_use']) ----> a
It seems like the third parameter of the url is being passed into the method (by codeigniter?), but can't work out why the array indexes seem to be set, all I can think is that php is converting the string to an int, so $args['whatever_index_I_use'], becomes $args[0]??
Not sure if this is a codeigniter thing or me missing a subtlety of php.
Much appreciate anyone who can explain what's going on.
Thanks.

Answer 1

I don't know if this is a bug or a expected behavior, but in the Strings docs there's a comment that show exactly what are you experiencing. If you use a text and index of the string it will return the first char. To avoid it, check first if the argument is an array or a string:
if(is_array($args)) {
echo($args['first_name']);
}

Answer 2

To complete #SérgioMichels answer, the reason for that is because PHP is expecting an integer as the given index. When you give it a string, PHP will cast the string into an integer, and assuming that the string does not start with a number, type casting will return 0 otherwise, it will return the leading number.
$str = 'abcdefghi';
var_dump($str['no_number']); // Outputs: string(1) "a"
var_dump($str['3something']); // Outputs: string(1) "d"

Answer 3

To specifically answer your question - this will solve your bug:
function get_details($args='')
{
if (is_array($args))
{
$first_name = $args['first_name'];
}
else
{
$first_name = $this->uri->segment(3);
}
... do some other stuff ...
}
But you have some issues with your code. Firstly you state that you call the method as
<domain>/<controller>/get_details/abcd/efgh
but you dont accept the "efgh" variable in your controller. To do this, you need to change the function to
function get_details($first, $last)
in which case you can now just call the function as
$this->get_details('abcd', 'efgh');
and now you dont even need to test for arrays etc, which is a better solution IMO.
If you decide to stick with arrays, change:
$first_name = $this->uri->segment(3);
to
$first_name = $args;
because by definition - $args IS The 3rd URI segment.