[RESOLVED] 2. A series of function questions, one at a time.

bluetonic

$a1=array("a","b","c","d");
$a2=array("Cat","Dog","Horse","Cow");
print_r(array_combine($a1,$a2));

result:
Array ( [a] => Cat => Dog [c] => Horse [d] => Cow )

Why does $a2[1] produce Dog but $a2 doesn't product anything?

My real question is why does the integer key work but not the 'b'? How does it know what the '1' is referring to?

laserlight

bluetonic wrote:
Why does $a2[1] produce Dog but $a2 doesn't product anything?

Why do you think $s2 exists?

bluetonic wrote:
My real question is why does the integer key work but not the 'b'? How does it know what the '1' is referring to?

Look at a print_r of $a2:

$a2=array("Cat","Dog","Horse","Cow");
print_r($a2);

It should be clear that $a2, or more correctly, $a2['b'], does not exist. The print_r of the result of the array_combine is not relevant here.

bluetonic

I though it exists b/c of the combined array:
Array ( [a] => Cat => Dog [c] => Horse [d] => Cow )

laserlight

bluetonic wrote:
I though it exists b/c of the combined array:
Array ( [a] => Cat => Dog [c] => Horse [d] => Cow )

Read the PHP manual concerning [man]array_combine/man. You will see that, like array_chunk(), it returns the modified array rather than modifying what you pass to it.

bluetonic

I am still having trouble understanding what good a modified array offers. If the nature of the array isn't being changed, what is the point of modifying the array? I mean, you don't use PHP to simply echo arrays.

laserlight

bluetonic wrote:
I am still having trouble understanding what good a modified array offers. If the nature of the array isn't being changed, what is the point of modifying the array?

Let's try this instead:

<?php
$a1 = array("a", "b", "c", "d");
$a2 = array("Cat", "Dog", "Horse", "Cow");
$a2 = array_combine($a1, $a2);
print_r($a2);
echo "<br \>\n" . $a2['b'];

Now, you see that after the result of the array_combine() is assigned back to $a2, $a2['b'] exists.

bluetonic

so is it safe to say that PHP functions (for the most part) really serve no purpose until a you "redefine" the variable so that it "redifines" the array?

laserlight

bluetonic wrote:
so is it safe to say that PHP functions (for the most part) really serve no purpose until a you "redefine" the variable so that it "redifines" the array?

No. As was pointed out to you in your previous thread, you might want to keep the original array. Furthermore, some functions operate on their argument(s), e.g.,

<?php
$a2 = array("Cat", "Dog", "Horse", "Cow");
print_r($a2);
echo "<br />\n";
sort($a2);
print_r($a2);

bluetonic

I think I am getting closer to understanding. I guess my source of confusion is that you can run an array through a function and print the result, but what you are seeing isn't what you really have.
For example,
$a=array("a"=>"Cat","b"=>"Dog","c"=>"Horse","d"=>"Cow");
print_r(array_chunk($a,2));
results:
Array ( [0] => Array ( [0] => Cat [1] => Dog )
[1] => Array ( [0] => Horse [1] => Cow ) )

But use can't echo $a[0][0] to product cat, you must echo $a['a'];
For the first one to work, you must redefine $a prior to the print_r

laserlight

bluetonic wrote:
I guess my source of confusion is that you can run an array through a function and print the result, but what you are seeing isn't what you really have.

You are looking at the print_r of the return value of the function. If you do not save that return value in a variable, then you are unable to do anything more with it.

bluetonic

thanks!