I have an array called followers and I would like to know how I could get the objectAtIndex $a of the array in PHP.
My current code is this, but it doesn't work:
$followers = anArray....
$returns = array();
for ($a = 1; $a <= $numberOfFollowers; $a++) {
$follower = $followers[$a];
echo $follower;
$query = mysql_query("query....");
if (!$query) {}
while ($row = mysql_fetch_assoc($query)) {
}
}
edit--- This is how I get the followers:
$followers = array();
while ($row = mysql_fetch_array($querys)) {
$followers[] = $row['followingUserID'];
}
$numberOfFollowers = count($followers);
Why not do a foreach(), like this?
$followers = array();
$returns = array();
foreach($followers as $index => $follower){
echo $follower;
$query = mysql_query("query....");
if (!$query) {}
while ($row = mysql_fetch_assoc($query)) {
}
}
I don't know what you are cooking with this, but to me, this is a huge cannon shooting towards the DB. Try to optimize your queries into a single one. Don't ever imagine DB fetches with a loop in your mind.
It looks like every element of $followers is a value returned from mysql_fetch_assoc(). Each element will be an associative array, and when you echo it I would expect to see it echoed as the string 'Array', since that is PHP's usual behaviour.
One point to observe is that when you create an empty array using array() and then populate it using assignments of the form $myarray[] = ..., the resulting array will be zero-indexed. That is, the keys of the array will start at 0, not at 1. So instead of for ($a = 1; $a <= $numberOfFollowers; $a++) {, you need to use for ($a = 0; $a < $numberOfFollowers; $a++) {, or go for the solution suggested by #Shef and use foreach.
Your problem might arise because $followers contains only one element, and because of the off-by-one error, you are not seeing any output. Turn on error reporting by adding this line at the start of your script:
error_reporting(E_ALL & ~E_STRICT);
If I am right then with your current code, you should see a Notice: Undefined index: 1 ...
Related
I have 4 arrays, each one holds another column of a table, I would like to create one array with the data ordered per array[$i]. All arrays have the same number of values: $namesArr, $folderArr, $updatedAt, $valuesArr .
I would like my new array to be contain:
$namesArr[0], $folderArr[0], $updatedAt[0], $valuesArr[0],
$namesArr[1], $folderArr[1], $updatedAt[1], $valuesArr[1],
$namesArr[2], $folderArr[2], $updatedAt[2], $valuesArr[2],
...
I guess the solution is pretty simple, but I got stuck :(
Can anyone help?
I would do something like:
$arr = array_map(function () { return func_get_args(); },$namesArr, $folderArr, $updatedAt, $valuesArr);
You can use foreach loop to merge 4 arrays:
foreach ($namesArr as $key => $value) {
$arr[$key][] = $value;
$arr[$key][] = $folderArr[$key];
$arr[$key][] = $updatedAt[$key];
$arr[$key][] = $valuesArr[$key];
}
Thus $arr will be the merged array
<?php
$newArr = array();
for ($i = 0; $i < count($namesArr); $i++)
{
$newArr[$i][0] = $namesArr[$i];
$newArr[$i][1] = $folderArr[$i];
$newArr[$i][2] = $updatedAt[$i];
$newArr[$i][3] = $valuesArr[$i];
}
?>
Explanation
What this will do is iterate depending on how many elements there are in $namesArr.
I utilised a multidimensional array here so that the first set of square brackets is effectively the "row" in a table, and the second set of square brackets are the "column" of a table.
do the following way:
while($db->query($sql)){
$namesArr[] =$db->f('names');
$folderArr[]=$db->f('folder');
$updatedAt[]=$db->f('updated');
$valuesArr[]=$db->f('values');
}
$result = array();
for ( $i = 10; $i < 101; $i = $i + 10 ){
$result[] = $i;
}
echo implode(", ", $result);
Hello...I'm new to PHP, and this really confused me, declaring a variable array even the code will work without it.
I've found this code here in the forum, regarding the removal of the comma in a for loop. I was wondering what variable is called when it is echoed? Is it the $result = array() or the $result[]? I've tried to remove the $result = array(); and the code still work, is that mean, is it ok to just remove the $result = array();? Does it have some coding issues if it is removed?
The line $result = array(); is used to declare an array.
It's a better approach to use this especially when you have some other previously specified variable $result storing some other value. Mentioning this first line will reset any previously assigned value to $result and declare it as an array datatype.
$result[] = $i; means the value of $i keeps apppending to $result every time.
I'm writing a script and it seems like a bit of a ballache so I came on SO to ask for a little help making my script more dynamic so I create a better version of what I'm doing. I've read into variable variables but I'm still stuck on how I'd use them.
I'll obviously shorten this down but my current script is:
$a0 = $tags['items'][0]['snippet']['tags'];
$a1 = $tags['items'][1]['snippet']['tags'];
$a2 = $tags['items'][2]['snippet']['tags'];
if (!is_array($a0)) { $a0 = array(); }
if (!is_array($a1)) { $a1 = array(); }
if (!is_array($a2)) { $a2 = array(); }
$a0 = array_map('strtolower', $a0);
$a1 = array_map('strtolower', $a1);
$a2 = array_map('strtolower', $a2);
array_count_values(array_merge($a0,$a1,$a2));
I'm looking for a way to dynamically create the variables (For example using an index in a while loop rather than creating these variables uniquely. This obviously is fine on a small scale, but i've currently done 50 of these for each and it's causing serious time problems. Any help is much appreciated
Treat the whole $tags variable as an array and you can do this, similar to the strtolower array_map you have already:
$tagItems = [];
foreach($tags['items'] as $item) {
if (!$item['snippet']['tags'] || !is_array($item['snippet']['tags'])) {
continue;
}
foreach($item['snippet']['tags'] as $tag) {
$tag = strtolower($tag);
if (!isset($tagItems[$tag])) {
$tagItems[$tag] = 0;
}
$tagItems[$tag]++;
}
}
As #FranzGleichmann says, try not to use variable variables, which are a smell and potential security risk, but instead rethink how you want to approach the problem.
You should be able to produce the same output that you get from array_count_values with a nested foreach loop.
foreach ($tags['items'] as $x) { // loop over the list of items
foreach ($x['snippet']['tags'] as $tag) { // loop over the tags from each item
$tag = strtolower($tag);
if (!isset($counts[$tag])) $counts[$tag] = 0;
$counts[$tag]++; // increment the tag count
}
}
No need to create 100 variables. That would cause a headache. Instead, use a simple loop function.
$b = array();
for ($n=1; $n<=100; $n++) {
$a = $tags['items']["$n"]['snippet']['tags'];
if (!is_array($a)) { $a = array(); }
$a = array_map('strtolower', $a);
array_count_values(array_merge($b,$a));
}
I hope it works! Have a nice coding
I would write this in a comment but i will a long one,
Variable Variable, is simply the value of the original var assigned as a var name, which means:
$my_1st_var = 'im_1st';
//use $$
$$my_1st_var = 'im_2nd'; //that is the same of $im_1st='im_2nd';
//results
echo $my_1st_var; // >>> im_1st
echo $im_1st; // >>> im_2nd
that means i created a new var and called it the value of the 1st var which is im_1st and that makes the variable name is $im_1st
also you can set multiple values as a var name:
$var0 = 'a';
$var1 = 'b';
$var2 = 'c';
$var3 = '3';
//we can do this
${$var0.$var1} = 'new var 1'; //same as: $ab = 'new var 1';
${$var1.$var2.$var3} = 'im the newest'; //same as: $bc3 = 'im the newest';
//set a var value + text
${$var0.'4'.$var1} = 'new?'; //same as: $a4b = 'new?';
also $GOLBALS[]; is some kind of $$
hope it helps you understanding what is hard for you about $$ ;)
Alright so dynamically creating variables is easy is a script language like PHP.
You could make $a an array, and instead of $a0, $a1, ... use $a[$i] where $i goes from 0 to 50 or more.
Or you could use this nice funky syntax: ${'a'.$i}. For example:
$i = 0;
${'a'.$i} = 'foobar';
echo $a0; // will output foobar
However you shouldn't do any of this.
What you should do is think about what you are trying to achieve and come up with a different algorithm that doesn't require dynamically named variables.
In this case, something like this looks like it would do the job:
$result = [];
foreach ( $tags['items'] as $item ) {
if ( is_array($item['snippet']['tags']) ) {
$result = array_merge($result, array_map('strtolower',$item));
}
}
array_count_values($result);
This is obviously not tested and from the top of my head, but I hope you get the idea. (EDIT: or check the other answers with similarly rewritten algorithms)
I have an array declared above the beginning of a for loop as: $array = array();.
Now, in the for loop I start inserting values into it.
At some point I make one of its index as another array as $array[$j]=array();
And insert some values like, $array[$j][$l] = id; and so on.
Now, when I use print_r ($array); inside the loop I get the expected value of the array.
But outside the loop this newly created array (2-D) is getting lost and I am getting only a 1-D array as an output.
Can someone please tell me where the problem could lie?
The following code works properly. Perhaps you are switching your variables as strager suggests.
<?php
$array = array();
for ($i = 0; $i < 10; $i+=1) {
if ($i == 5) {
$array[$i] = array('value 1', 'value 2');
} else {
$array[$i] = $i;
}
}
print_r($array);
?>
I need to combine two foreach statement into one for example
foreach ($categories_stack as $category)
foreach ($page_name as $value)
I need to add these into the same foreach statement
Is this possible if so how?
(I am not sure I have understood your question completely. I am assuming that you want to iterate through the two lists in parallel)
You can do it using for loop as follows :
$n = min(count($category), count($value));
for($c = 0; $c < $n; $c = $c + 1){
$categories_stack = $category[$c];
$pagename = $value[$c];
...
}
To achieve the same with foreach you need a function similar to Python's zip() function.
In Python, it would be :
for categories_stack, pagename in zip(categories, values):
print categories_stack, pagename
Since PHP doesn't have a standard zip() function, you'll have to write such a function on your own or go with the for loop solution.
You can do nested foreachs if that's what you want. But without knowing more of your data, it's impossible to say if this helps:
foreach ($categories_stack as $category) {
foreach ($page_name as $value) {
}
}
Probably you want to print out all pages in a category? That probably won't work, so can you give a bit more info on how the arrays look like and relate to each other?
This loop will continue to the length of the longest array and return null for where there are no matching elements in either of the arrays. Try it out!
$a = array(1 => "a",25 => "b", 10 => "c",99=>"d");
$b = array(15=>1,5=>2,6=>3);
$ao = new ArrayObject($a);
$bo = new ArrayObject($b);
$ai = $ao->getIterator();
$bi = $bo->getIterator();
for (
$ai->rewind(),$bi->rewind(),$av = $ai->current(),$bv = $bi->current();
list($av,$bv) =
array(
($ai->valid() ? $ai->current() : null),
($bi->valid() ? $bi->current() : null)
),
($ai->valid() || $bi->valid());
($ai->valid() ? $ai->next() : null),($bi->valid() ? $bi->next() : null))
{
echo "\$av = $av\n";
echo "\$bv = $bv\n";
}
I cannot really tell from the question exactly how you want to traverse the two arrays. For a nested foreach you simply write
foreach ($myArray as $k => $v) {
foreach ($mySecondArray as $kb => $vb {
}
}
However you can do all sorts of things with some creative use of callback functions. In this case an anonymous function returning two items from each array on each iteration. It's then easy to use the iteration value as an array or split it into variables using list() as done below.
This also has the added benefit of working regardless of key structure. I's purely based on the ordering of array elements. Just use the appropriate sorting function if the elements are out of order.
It does not worry about the length of the arrays as there is no error reported, so make sure you keep an eye out for empty values.
$a = array("a","b","c");
$b = array(1,2,3);
foreach (
array_map(
create_function(
'$a,$b', 'return array($a,$b);'
)
,$a,$b
)
as $value
)
{
list($a,$b) = $value;
echo "\$a = $a\n";
echo "\$b = $b\n";
}
Output
$a = a
$b = 1
$a = b
$b = 2
$a = c
$b = 3
Here's another one for you that stops on either of the lists ending. Same as using min(count(a),count(b). Useful if you have arrays of same length. If someone can make it continue to the max(count(a),count(b)) let me know.
$ao = new ArrayObject($a);
$bo = new ArrayObject($b);
$ai = $ao->getIterator();
$bi = $bo->getIterator();
for (
$ai->rewind(),$bi->rewind();
$av = $ai->current(),$bv=$bi->current();
$ai->next(),$bi->next())
{
echo "\$av = $av\n";
echo "\$bv = $bv\n";
}
This is where the venerable for loop comes in handy:
for(
$i = 0,
$n = sizeof($categories_stack),
$m = sizeof($page_name);
$i < $n && $i < $m;
$i++
) {
$category = $categories_stack[$i];
$value = $page_name[$i];
// do stuff here ....
}
Surely you can just merge the arrays before looping?
$data = array_merge($categories_stack, $page_name);
foreach($data AS $item){
...
}
Do the array elements have a direct correspondence with one another, i.e. is there an element in $page_name for each element in $categories_stack? If so, just iterate over the keys and values (assuming they have the same keys):
foreach ($categories_stack as $key => $value)
{
$category = $value;
$page = $page_name[$key];
// ...
}
Could you just nest them with variables outside the scope of the foreach, or prehaps store the content as an array similar to a KVP setup? My answer is vague but I'm not really sure why you're trying to accomplish this.