I'm having a trouble getting my array content when using a declared variable as my array indexes shown below.
$indexes = "[0][1][0][1]";
$code = $params["smv_code"].$indexes;
this returns an "Array to string conversion error";
Note that the $indexes is dynamic depends on the "parent_0_1_0_1" params content of the array index.
the . operator just does a string concatenation - it's not going to work for code like that. I don't think PHP has the ability to interpret raw code like that - at least not safely. (You can always use eval, but there are serious security concerns for using something like that - injection, etc.).
I would suggest just traversing the array "manually" through interpreting the indexes yourself. Change the $indexes to "0,1,0,1" and do the following:
$index_array = explode(',',$indexes)
$code = $params["smv_code"];
foreach($index_array as $i) {
$code=$code[$i];
}
$code at the end should be the value you're looking for.
Related
Let's say I have a variable which is an initialized, empty array.
$cache = [];
The data in this array can be created like this, for example (please excuse the crude code and variable/key names, they're here for the sake of this example only):
for ($row in $someOtherArray) {
$cache[$row['id']][] = $row['data'];
}
Since $cache is a PHP array, I don't really need to initialize $cache[$row['id']] to also be an array. However, I sometimes encounter code like this:
for ($row in $someOtherArray) {
if (!isset($cache[$row['id']])) {
$cache[$row['id']] = [];
}
$cache[$row['id']][] = $row['data'];
}
Above, the sub-array is explicitly initialized as an empty array. Is it useful somehow? For example - does it help the interpreter in some way? Or is it only a developer being overzealous?
It's unnecessary as far as PHP is concerned. PHP will implicitly create any number of sub-arrays for you using the $foo[$bar][] syntax. It may be required for business logic, though not in this particular arrangement; it's simply redundant here. If the value assignment is somehow separate logic, but you still want to ensure that at least an empty array exists for the key, that's the only time it makes sense.
Once you have initialised a variable as an array, you can use array specific methods on that variable. For example array_push(), array_map() etc..
i know this
$var1 = "10";
$var2 = "var1";
then
echo $$var2 gives us 10
i want to this with array
i have array
$intake_arr = array(5=>10,7=>20,8=>30,9=>40,10=>50,11=>60,12=>70);
i have some logic that will pick one array from set of array , all array will look like $intake_arr
if i do this $target_arr = "intake_arr";
then can $$target_arr[5] will yield 10? i tried but i didnt that 10 value, how can i achieve this with array
Your statement ($$target_arr[5]) is ambiguous. PHP doesn't know what you actually want to say: Do you mean: use $target_arr[5]'s value and prepend the $, to use that as a variable, or do you want to use the value of $target_arr, and get the fifth element of that array?
Obviously it's the latter, but PHP doesn't know that. In order to disambiguate your statement, you have to use curly braces:
${$target_arr}[5];
That'll yield 10. See the manual on variable variables for details
Note:
As people said in comments, and deleted answers: variable variables, like the one you're using is risky business. 9/10 it can, and indeed should be avoided. It makes your code harder to read, more error prone and, in combination with the those two major disadvantages, this is the killer: it makes your code incredibly hard to debug.
If this is just a technical exercise, consider this note a piece of friendly advice. If you've gotten this from some sort of tutorial/blog or other type of online resource: never visit that site again.
If you're actually working on a piece of code, and you've decided to tackle a specific problem using variable vars, then perhaps post your code on code-review, and let me know, I'll have a look and try to offer some constructive criticism to help you on your way, towards a better solution.
Since what you're actually trying to do is copying an array into another variable, then that's quite easy. PHP offers a variety of ways to do that:
Copy by assignment:
PHP copies arrays on assignment, by default, so that means that:
$someArray = range(1,10);//[1,2,3,4,5,6,7,8,9,10]
$foo = $someArray;
Assigns a copy of $someArray to the variable $foo:
echo $foo[0], ' === ', $someArray[0];//echoes 1 === 1
$foo[0] += 123;
echo $foo[0], ' != ', $someArray[0];//echoes 123 != 1
I can change the value of one of the array's elements without that affecting the original array, because it was copied.
There is a risk to this, as you start working with JSON encoded data, chances are that you'll end up with something like:
$obj = json_decode($string);
echo get_class($obj));//echoes stdClass, you have an object
Objects are, by default, passed and assigned by reference, which means that:
$obj = new stdClass;
$obj->some_property = 'foobar';
$foo = $obj;
$foo->some_property .= '2';
echo $obj->some_property;//echoes foobar2!
Change a property through $foo, and the $obj object will change, too. Simply because they both reference exactly the same object.
Slice the array:
A more common way for front-end developers (mainly, I think, stemming from a JS habbit) is to use array_slice, which guarantees to return a copy of the array. with the added perk that you can specify how many of the elements you'll be needing in your copy:
$someArray = range(1,100);//"large" array
$foo = array_slice($someArray, 0);//copy from index 0 to the end
$bar = array_slice($someArray, -10);//copy last 10 elements
$chunk = array_slice($someArray, 20, 4);//start at index 20, copy 4 elements
If you don't want to copy the array, but rather extract a section out of the original you can splice the array (as in split + slice):
$extract = array_splice($someArray, 0, 10);
echo count($someArray);//echoes 90
This removes the first 10 elements from the original array, and assigns them to $extract
Spend some time browsing the countless (well, about a hundred) array functions PHP offers.
${$target_arr}[5]
PHP: Variable variables
Try this one:
$intake_arr = array(5=>10,7=>20,8=>30,9=>40,10=>50,11=>60,12=>70);
$target_arr = 'intake_arr';
print ${$target_arr}[5]; //it gives 10
For a simple variable, braces are optional.But when you will use a array element, you must use braces; e.g.: ${$target_arr}[5];.As a standard, braces are used if variable interpolation is used, instead of concatenation.Generally variable interpolation is slow, but concatenation may also be slower if you have too many variables to concatenate.Take a look here for php variable variables http://php.net/manual/en/language.variables.variable.php
I have a string like this stored in mysql table:
?name1=value1&name2=value2&name3=value3
originally this data was only going to be used to send GET data to another script but now i find myself needing it for other things.
is there a predefined function in PHP for turning these pairs into variable or an array? or will I have to do it manually?
The (poorly-named) PHP function parse_str can do this, though you will need to first trim off the initial question mark.
$arr = array();
parse_str($str, $arr);
print_r($arr);
There are some caveats to this function alluded to in the manual page:
If you call it without the second array parameter it will write the values into the current scope as local variables. This can be dangerous if the string contains keys that may change the value of variables already present in your program.
The magic_quotes_gpc setting affects how this function operates, since this is the routine used internally by PHP to decode query strings and urlencoded POST bodies.
If you need a portable solution that is not affected by the magic_quotes_gpc setting then it's reasonably straightforward to write a decoding function manually, using urldecode to handle the value encoding:
function parseQueryString($queryString) {
$result = array();
$pairs = explode("&", $queryString);
foreach ($pairs as $pair) {
$pairArr = split("=", $pair, 2);
$result[urldecode($pairArr[0])] = urldecode($pairArr[1]);
}
return $result;
}
This solution will probably be slightly slower than the built-in parse_args function, but has the benefit of consistent behavior regardless of how PHP is configured. Of course you will again need to first strip off the ? from the beginning, which is not included in either example.
Var_export Might be useful.
$arr=?name1=value1&name2=value2&name3=value3
var_export($arr);
(NOTE: This is a follow up to a previous question, How to pass an array within a query string?, where I asked about standard methods for passing arrays within query strings.)
I now have some PHP code that needs to consume the said query string- What kind of query string array formats does PHP recognize, and do I have to do anything special to retrieve the array?
The following doesn't seem to work:
Query string:
?formparts=[a,b,c]
PHP:
$myarray = $_GET["formparts"];
echo gettype($myarray)
result:
string
Your query string should rather look like this:
?formparts[]=a&formparts[]=b&formparts[]=c
If you're dealing with a query string, you are looking at the $_GET variable. This will contain everything after the ? in your previous question.
So what you will have to do is pretty much the opposite of the other question.
$products = array();
// ... Add some checking of $_GET to make sure it is sane
....
// then assign..
$products = explode(',', $_GET['pname']);
and so on for each variable. I must give you a full warning here, you MUST check what comes through the $_GET variable to make sure it is sane. Otherwise you risk having your site compromised.
I had no idea to correctly form the title of this question, because I don't even know if what I'm trying to do has a name.
Let's say I've got an external file (called, for instance, settings.txt) with the following in it:
template:'xaddict';
editor:'true';
wysiwyg:'false';
These are simple name:value pairs.
I would like to have php take care of this file in such a way that I end up with php variables with the following values:
$template = 'xaddict';
$editor = 'true';
$wysiwyg = 'false';
I don't know how many of these variables I'll have.
How should i go and do this?
The data inside the file is in simple name:value pairs. No nesting, no complex data. All the names need to be converted to $name and all the values need to be converted to 'value', disregarding whether it is truly a string or not.
$settings = json_decode(file_get_contents($filename));
assuming your file is in valid JSON format. If not, you can either massage it so it is or you'll have to use a different approach.
Do you want 'true' in "editor:'true'" to be interpreted as a string or as a boolean? If sometimes string, sometimes boolean, how do you know which?
If you have "number='9'" do you want '9' interpreted as a string or an as an integer? Would '09' be a decimal number or octal? How about "number='3.14'": string or float? If sometimes one, sometimes the other, how do you know which?
If you have "'" (single quote) inside a value is it escaped? If so, how?
Is there any expectation of array data?
Etc.
Edit: This would be the simplest way, imo, to use your example input to retrieve your example data:
$file = 'test.csv';
$fp = fopen($file, 'r');
while ($line = fgetcsv($fp, 1024, ':')) {
$$line[0] = $line[1];
}
If you use JSON, you can use something like:
extract(json_decode(file_get_contents('settings.json')));
Using extract may be dangerous, so I suggest to store these settings in an array:
$settings = json_decode(file_get_contents('settings.json'));
You should read your file to an array, with the file() function, then you should cycle on it: for each line (the file() function will return an array, one line per item), check if the line is not blank, then explode() on the ":" character, trim the pieces, and put them into an array.
You will end up win an array like this:
[template] = xaddict
[editor] = true
then you can use this information.
Do not automatically convert this into local variables: it's a great way to introduce security risks, and potentially very obscure bugs (local variables obscured by those introduced by this parsing).