I have created few different strings with similar names, and I would like to display them all.
However, I will need to do this dynamically, because I will adding more of them, later on.
These strings are called:
$group1
$group2
$group3
$group4
My idea is to somehow count them all, and then display them with for loop. I just need help with counting part.
Though arrays are definitely the superior and appropriate solution in this case, since you insist in the comments that separate variables are required, you can solve this using a while loop to check for the existence of such consecutively named variables, creating the variable names dynamically with {}.
For example:
$group1 = '123';
$group2 = '456';
$group3 = '789';
$i=1;
while ($string = ${'group'.$i}) {
echo $string;
$i++;
}
Note how ${'group'.$i} dynamically creates each variable name. Also, naturally this approach would fail if the variables are not named consecutively (e.g. if you have $group1 followed by $group3). As said, you should definitely use an array for this.
See a live demo
Associative arrays are designed exactly for this:
$arr = array(
"group1" => "string1",
"group2" => "string2",
"group3" => "string3",
"group4" => "string4",
);
Now to get the length of your array:
$num = count($arr);
To access the first element
$firstElement = $arr["group1"];
Alternatively you can use an indexed array (access elements by their position):
$arr = array("string1", "string2", "string3", "string4");
$firstElement = $arr[0];
$num = count($arr);
you can use this to count+loop
$arr=array();
$add_to=array_push($arr,$group1);
$add_to=array_push($arr,$group2);
$add_to=array_push($arr,$group3);
$add_to=array_push($arr,$group4);
//count
echo count($arr);
//loop
foreach($arr as $key=>$value){
echo $value;
}
Related
I have an array that I want to rename so that the values are stored depending on what number the for loop is on. I tried something like this but its giving me an error.
for ($i =0;$i<4;$i++){
$array.$i = array();
push stuff into array;
}
So at the next iteration the array is called array1, then array2 and so forth. What is the best way to do this.
To literally answer your question:
$arrayName = 'array' . $i;
$$arrayName = array();
$$arrayName[] = ...
What you really want is a multidimensional array though:
$array[$i] = array();
$array[$i][] = ...;
You want to use variable variables, in which the double dollar sign indicates that the name of the variable is taken from a variable.
$varname = "array";
for ($i =0;$i<4;$i++){
$newvarname = $varname . $i
$$newvarname = new array()
push stuff into array;
}
I would add that in these cases, a simpler solution is often to use an array in which the desired variable names are indices. So instead of creating $array1, $array2, and so forth, you'd have:
$arrays = array (
'array1' => array(stuff),
'array2' => array(stuff),
'array3' => array(stuff),
'array4' => array(stuff)
}
At least, I find it easier to keep track of.
You should be able to reference the array using the $$ notation for variable variables (see: http://www.php.net/manual/en/language.variables.variable.php).
So, something like this should work (untested):
for ($i =0;$i<4;$i++){
$thisArrayName = 'array'.$i;
$$thisArrayName = array();
push stuff into array;
}
You need array of array
for ($i =0;$i<4;$i++){
$array[$i] = array();
push stuff into array;
}
$index = 0;
foreach ($sxml->entry as $entry) {
$array + variable index number here = array('title' => $title);
$index++;
}
I'm trying to change an array name depending on my index count. Is it possible to change variable name (ie. $array1, $array2 $array3 etc.) in the loop?
Edit:
After the loop has finished, I will generate a number number (depending on the count of $index) and then use this array... probably it's a stupid way of accomplishing what Im trying to do, but I don't have a better idea.
You might want to try this instead:
$index = 0;
$arrays = array();
foreach ($sxml->entry as $entry) {
$arrays[$index] = array('title' => $title);
$index++;
}
While it is technically possible to do what you are asking, using an array of arrays will probably work better from you.
This type of indexing is exactly what arrays are designed for, you have a lot of items and want to be able to refer to them by number.
Unless you have a very specific reason to use the name of the variable to represent it's number you will probably have a much simpler time using it's index in the outer array.
Yes you can user an associate array. Generating a string dynamically based on the iteration number and using that as a key in the array.
You can use variable variables. php.net
PHP supports Variable variables:
$num = 1;
$array_name = 'array' . $num;
$$array_name = array(1,2,3);
print_r($array1);
http://php.net/manual/en/language.variables.variable.php
So, I'm starting a new project and working with php for the first time.
I get that the average definition and functioning of arrays in php is actually pretty much a namevalue combo.
Is there some syntax, API, or other terminology for just a simple list of items?
I.e. inserting something like ['example','example2','example3','example4'] that I can just call based off their index position of the array, without having to go in and modify the syntax to include 0 => 'example', etc...
This is a very shortlived array so im not worried about long term accessibility
php arrays are simple to use. You can insert into an array like:
$array=array('a','b','c'.....);
Or
$array[]="a";
$array[]="b";
$array[]="c";
or
array_push($array, "a");
array_push($array, "b");
array_push($array, "c");
array_push($array, "d");
and call them by their index values:
$array[0];
this will give you a
$yourArray = array('a','b','c');
or
$yourArray[] = 'a';
$yourArray[] = 'b';
$yourArray[] = 'c';
will get you an array with integer index values instead of an associative one..
You still can use array as "classic" arrays in php, just the way you think.
For example :
<?php
$array = array("First", "Second", "Third");
echo $array[1];
?>
You can then add different values <?php $array[] = "Forth"; ?> and it will be indexed in the order you specified it.
Notice that you can still use it as an associative array :
<?php
$array["newValue"] = "Fifth";
$array[1] = "ReplaceTheSecond";
$array[10] = "";
?>
Arrays in PHP can either be based on a key, like 0 or "key" => "value", or values can just be "appended" to the array by using $array[] = 'value'; .
So:
$mine = array();
$mine[] = 'test';
$mine[] = 'test2';
echo $mine[0];
Would produce 'test';
Haven't tested the code.
I'm working with an array of data that I've changed the names of some array keys, but I want the data to stay the same basically... Basically I want to be able to keep the data that's in the array stored in the DB, but I want to update the array key names associated with it.
Previously the array would have looked like this: $var_opts['services'] = array('foo-1', 'foo-2', 'foo-3', 'foo-4');
Now the array keys are no longer prefixed with "foo", but rather with "bar" instead. So how can I update the array variable to get rid of the "foos" and replace with "bars" instead?
Like so: $var_opts['services'] = array('bar-1', 'bar-2', 'bar-3', 'bar-4');
I'm already using if(isset($var_opts['services']['foo-1'])) { unset($var_opts['services']['foo-1']); } to get rid of the foos... I just need to figure out how to replace each foo with a bar.
I thought I would use str_replace on the whole array, but to my dismay it only works on strings (go figure, heh) and not arrays.
The idea:
Get a list of all your array keys
Modify each one of them as you choose
Replace the existing keys with the modified ones
The code:
$keys = array_keys($arr);
$values = array_values($arr);
$new_keys = str_replace('foo', 'bar', $keys);
$arr = array_combine($new_keys, $values);
What this actually does is create a new array which has the same values as your original array, but in which the keys have been changed.
Edit: updated as per Kamil's comment below.
For the values you've provided
$var_opts['services'] = array('foo-1', 'foo-2', 'foo-3', 'foo-4');
var_dump($var_opts['services']);
foreach($var_opts['services'] as &$val) {
$val = str_replace('foo', 'bar', $val);
}
unset($val);
var_dump($var_opts['services']);
or if you want to change the actual keys
$var_opts['services'] = array('foo-1' => 1, 'foo-2' => 2, 'foo-3' => 3, 'foo-4' => 4);
var_dump($var_opts['services']);
foreach($var_opts['services'] as $i => $val) {
unset($var_opts['services'][$i]);
$i = str_replace('foo', 'bar', $i);
$var_opts['services'][$i] = $val;
}
var_dump($var_opts['services']);
I have an array:
$arr = array('foo', 'bar', 'bash', 'monkey', 'badger');
I want to have the elements in that array appear as the variables in my list():
list($foo, $bar, $bash, $monkey, $badger) = $data;
Without actually specifying the variables, I tried;
list(implode(",$", $arr)) = $data; and
list(extract($arr)) = $data;
But they don't work, I get:
Fatal error: Can't use function return value in write context
Does anyone have any idea whether this is possible?
UPDATE: more context:
I am getting a CSV of data from an API, the first row is column names, each subsequent row is data. I want to build an associative array that looks like this:
$data[0]['colname1'] = 'col1data';
$data[0]['colname2'] = 'col2data';
$data[0]['colname3'] = 'col3data';
$data[1]['colname1'] = 'col1data';
$data[1]['colname2'] = 'col2data';
$data[1]['colname3'] = 'col3data';
Before I do that, however, I want to make sure I have all the columns I need. So, I build an array with the column names I require, run some checks to ensure the CSV does contain all the columns I need. Once thats done, the code looks somewhat like this (which is executed on a foreach() for each row of data in the CSV):
//$data is an array of data WITHOUT string indexes
list( $col1,
$col2,
$col3,
...
$col14
) = $data;
foreach($colNames AS $name)
{
$newData[$i][$name] = $$name;
}
// Increemnt
$i++;
As I already HAVE an array of column name, I though it would save some time to use THAT in the list function, instead of explicitly putting in each variable name.
The data is cleaned and sanitised elsewhere.
Cheers,
Mike
I want to have the elements in that array appear as the variables in my list():
i think there is your problem in understanding. list() does not create a new list structure or variable, it can only be used to assign many variables at once:
$arr = array(1, 2, 3);
list($first, $second, $third) = $arr;
// $first = 1, $second = 2, $third = 3
see http://php.net/list for more information.
you are probably looking for an associative array. you can create it with the following code:
$arr = array('first' => 1, 'second' => 2, 'third' => 3);
// $arr['first'] = 1, …
If some rows in your input file are missing columns, you can't really know which one is missing. Counting the number of values and aborting or jumping to next row when less than expected should be enough.
... unless you set the rule that last columns are optional. I'll elaborate on this.
Your code sample is far for complete but it seems that your problem is that you are using arrays everywhere except when matching column names to cell values. Use arrays as well: you don't need individual variables and they only make it harder. This is one of the possible approaches, not necessarily the best one but (I hope) clear enough:
<?php
$required_columns = array('name', 'age', 'height');
$input_data = array(
array('John', 33, 169),
array('Bill', 40, 180),
array('Ashley', 21, 155),
array('Vincent', 13), // Incomplete record
array('Michael', 55, 182),
);
$output = array();
foreach($input_data as $row_index => $row){
foreach($required_columns as $col_index => $column_name){
if( isset($row[$col_index]) ){
$output[$row_index][$column_name] = $row[$col_index];
}
}
}
print_r($output);
?>
I've used $row_index and $col_index for simplicity.
Original answer, for historical purposes only ;-)
I can't really understand your specs but PHP features variable variables:
<?php
$arr = array('foo', 'bar', 'bash', 'monkey', 'badger');
foreach($arr as $i){
$$i = $i;
}
?>
Now your script has these variables available: $foo, $bar... It's quite useless and potentially dangerous but it does what you seem to need.
You are trying to use a language construct in a manner in which it's not meant to be used. Use variable variables as Alvaro mentioned.
$arr = array('foo', 'bar', 'bash', 'monkey', 'badger');
foreach ($arr as $index => $key) {
$$key = $data[$index];
}
or
$arr = array('foo', 'bar', 'bash', 'monkey', 'badger');
$result = array();
foreach ($arr as $index => $key) {
$result[$key] = $data[$index];
}
extract($result);
In short, do not use "list", use arrays and associated arrays. Write helper functions to make your code clearer.
why not immediatly call the vars like
$arr['foo']
or
$arr[0]
If you want to extract the elements of $data into the current context, you can do that with extract. You might find it useful to call array_intersect_key first to pare down $data to the elements that you want to extract.
May be try like this :
$arr = array('foo', 'bar', 'bash', 'monkey', 'badger');
$data = "$".implode(",", $arr);
echo str_replace(",", ",$", $data);