Why does the following code give me an error in php?:
$b = array("1" => "2")["1"];
Error I get is Parse error...
Help.
Unfortunately, in PHP, you need to do this:
$a = array("1" => "2");
$b = $a["1"];
It feels like your example should work because it does in other languages. But this is just the way PHP is.
Couple things. You can't pull immediately from arrays during creation, and keys of numerical values are automatically converted to integers, even if they're intended to be strings.
You can use a function to do this for you:
function Get($array, $key, $default = false)
{
if (is_array($array) === true)
{
settype($key, 'array');
foreach ($key as $value)
{
if (array_key_exists($value, $array) === false)
{
return $default;
}
$array = $array[$value];
}
return $array;
}
return $default;
}
And use it like this:
$b = Get(array("1" => "2"), "1"); // 2
If you don't need to access multi-dimensional arrays you can also use this shorter function:
function Get($array, $key, $default = false)
{
if (is_array($array) === true)
{
return (array_key_exists($value, $array) === true) ? $array[$value] : $default;
}
return $default;
}
Related
I have an array like
$arr = array(0 => array(id=>1,name=>"Apple"),
1 => array(id=>2,name=>"Orange"),
2 => array(id=>3,name=>"Grape")
);
I have written the code for searching the multidimensional array.
Here is it
function search($array, $key, $value)
{
$results = array();
search_r($array, $key, $value, $results);
return $results;
}
function search_r($array, $key, $value, &$results)
{
if (!is_array($array)) {
return;
}
if (isset($array[$key]) && $array[$key] == $value) {
$results[] = $array;
}
foreach ($array as $subarray) {
search_r($subarray, $key, $value, $results);
}
}
But it works only for exactly matching keywords.
What I need is, If I search for 'Gra' in this array. The function should return
array(0 => array(id=>1,name=>"Grape")
);
This seems to be something like mysql %LIKE% condition.How can this be done in PHP arrays ?
When checking if the string matches you can instead use strpos
strpos($strToCheck, 'Gra') !== false;//Will match if $strToCheck contains 'Gra'
strpos($strToCheck, 'Gra') === 0; //Will match if $strToCheck starts with 'Gra'
Note that the above is case sensitive. For case insensitivity you can strtoupper both strings before comparing use strripos instead.
In your example the check would become:
if (isset($array[$key]) && strpos($array[$key],$value) !== false) {
$results[] = $array;
}
You can use stristr function for string manipulations in php, and you'll don't have to think about different cases and cast them to uppercase.
stristr function is not case sensitive, so your code will like this
if (isset($array[$key]) && stristr($array[$key], $value) !== false) {
$results[] = $array;
}
Focussing on the line here that you wrote -
if (isset($array[$key]) && $array[$key] == $value) {
We can modify it to search for substrings, rather than exact match -
if (isset($array[$key]) && strpos($array[$key], $value)) {
This will try to find if the value is present somewhere in the content of $array[$key]
Hope it helps
hello i would like to create a function that checks if an etry contains some words.
for my login-script i would like to create a function that checks if the $_POST has some keywords in it.
therfor i have thought to create an array that contains the words i'm looking for like that:
function value_check($a, $b){
$haystack = array ($a, $b)
$words = array ("abc", "def");
if(strpos($haystack, $words) === true) {
return ($a or $b, or both where strpos === true);
}
return false;
}
and i would like to call that function by:
$valid_value = value_check($a, $b);
if ($valid_value['a'] === true) {
//do something
}
if ($valid_value['b'] === true) {
//do something
}
thanks alot.
Okay, to clarify my question i would like to shorten my code. instead of using:
...else if ($a === "abc" || $a === "Abc" ) {
$errors['a'][] = "text";
}else if ($b === "def" || $a === "Def" ) {
$errors['b'][] = "text";
}
i thought i can do it a little bit more comfortable while using a function that checks easily if there is a that specific string in that array. hope it will be clear now. thanks.
Read this in_array for search in array. And this explode for creating an array from a string like Ascherer suggested.
function value_check ($haystack) {
foreach ($words as $element) {
if (in_array($element,$haystack) {
$result[] = $element;
}
}
return $result;
}
a call
$somestuff = array($a,$b);
$valid_value = value_check ($somestuff);
foreach ($valid_value as $value) {
// do something
}
In Python I can use "get" method to get value from an dictionary without error.
a = {1: "a", 2: "b"}
a[3] # error
a.get(3, "") # I got empty string.
So I search for a common/base function that do this:
function GetItem($Arr, $Key, $Default){
$res = '';
if (array_key_exists($Key, $Arr)) {
$res = $Arr[$Key];
} else {
$res = $Default;
}
return $res;
}
Have same function basicly in PHP as in Python?
Thanks:
dd
isset() is typically faster than array_key_exists(). The parameter $default is initialized to an empty string if omitted.
function getItem($array, $key, $default = "") {
return isset($array[$key]) ? $array[$key] : $default;
}
// Call as
$array = array("abc" => 123, "def" => 455);
echo getItem($array, "xyz", "not here");
// "not here"
However, if an array key exists but has a NULL value, isset() won't behave the way you expect, as it will treat the NULL as though it doesn't exist and return $default. If you expect NULLs in the array, you must use array_key_exists() instead.
function getItem($array, $key, $default = "") {
return array_key_exists($key, $array) ? $array[$key] : $default;
}
Not quite. This should behave the same.
function GetItem($Arr, $Key, $Default = ''){
if (array_key_exists($Key, $Arr)) {
$res = $Arr[$Key];
} else {
$res = $Default;
}
return $res;
}
The first line in your function is useless, as every code path results in $res being overwritten. The trick is to make the $Default parameter optional as above.
Keep in mind that using array_key_exists() can cause significant slowdowns, especially on large arrays. An alternative:
function GetItem($Arr, $Key, $Default = '') {
return isset($Arr[$Key]) ? $Arr[$Key] : $Default;
}
There is no base function to do that in my mind.
Your GetItem is a good way to do what you wanna do :)
Yes. or
function GetItem($Arr, $Key, $Default) {
return array_key_exists($Key, $Arr)
? $Arr[$Key]
: $Default;
}
php7 is out for a long time now so you can do
$Arr[$Key] ?? $default
I'm writing a function named all to check all elements inside an array $arr, returning a single boolean value (based of $f return value). This is working fine passing custom functions (see the code with $gte0 been passed to all).
However sometimes one want just check that an array contains all true values: all(true, $arr) will not work becase true is passed as boolean (and true is not a function name). Does PHP have a native true() like function?
function all($f, array $arr)
{
return empty($arr) ? false : array_reduce($arr, function($v1, $v2) use ($f) {
return $f($v1) && $f($v2);
}, true);
}
$test = array(1, 6, 2);
$gte0 = function($v) { return $v >= 0; }
var_dump(all($gte0, $test)); // True
$test = array(true, true, false);
$id = function($v) { return $v; } // <-- this is what i would avoid
var_dump(all($id, $test)); // False
all(true, $test); // NOT WORKING because true is passed as boolean
all('true', $test); // NOT WORKING because true is not a function
EDIT: another way could be checking $f in all function:
$f = is_bool($f) ? ($f ? function($v) { return $v; }
: function($v) { return !$v; } ): $f;
After adding this, calling all with true is perfectly fine.
intval might do what you're looking for (especially as the array only contains integers in your example):
var_dump(all('intval', $test)); // False
However, many types to integer conversions are undefined in PHP and with float this will round towards zero, so this might not be what you want.
The more correct "function" would be the opposite of boolean true: empty, but it's not a function, so you can't use it (and invert the return value):
var_dump(!all('empty', $test)); // Does not work!
And there is no function called boolval or similar in PHP, so write it yourself if you need it ;)
Additionally your all function could be optimized. While iterating, if the current result is already FALSE, the end result will always be FALSE. And no need to call $f() n * 2 times anyway:
function all($f, array $arr)
{
$result = (bool) $arr;
foreach($arr as $v) if (!$f($v)) return FALSE;
return $result;
}
Edit: knittl is right pointing to array_filter, it converts to boolean with no function given which seems cool as there is no "boolval" function:
function all($f, array $arr)
{
return ($c = count($arr))
&& ($f ? $arr = array_map($f, $arr) : 1)
&& $c === count(array_filter($arr));
}
var_dump(all(0, $test)); // False
Making the first function parameter optional will do you a proper bool cast on each array element thanks to array_filter.
Better to pass in a function to map the values to booleans that you can then reduce to a final value.
function all($map, $data) {
if (empty($data)) { return false; }
$reduce = function($f, $n) {
return $f && $n;
};
return array_reduce(array_map($map, $data), $reduce, true);
}
$gte0 = function($v) { return $v >= 0; };
$gte2 = function($v) { return $v >= 2; };
$data = array(1, 2, 3, 4, 5);
var_dump(all($gte0, $data));
var_dump(all($gte2, $data));
Then the result of the function remains expectant but the test can be slotted in as needed. You can go a step further and allow both the map and reduce function to be passed in.
function mr($map, $reduce, $data) {
return array_reduce(array_map($map, $data), $reduce, true);
}
You could use PHP's array_filter function, it will remove all 'falsy' values from an array if no callback is specified:
$a = array ( true, true, false );
var_dump($a == array_filter($a));
There isn't any true() function in PHP, you should compare the value to true.
try
return ($f === $v1) && ($f === $v2);
instead of
return $f($v1) && $f($v2);
I think this should work:
function all($f, array $arr)
{
return empty($arr) ? false : array_reduce($arr, function($v1, $v2) use ($f) {
return $f($v1) && $f($v2);
}, true);
}
function isTrue($a)
{
return true === $a;
}
all("isTrue", $test);
I'm working on a program that uses PHP's internal array pointers to iterate along a multidimensional array. I need to get an element from the current row, and I've been doing it like so:
$arr[key($arr)]['item']
However, I'd much prefer to use something like:
current($arr)['item'] // invalid syntax
I'm hoping there's a function out there that I've missed in my scan of the documentation that would enable me to access the element like so:
getvalue(current($arr), 'item')
or
current($arr)->getvalue('item')
Any suggestions?
I very much doubt there is such a function, but it's trivial to write
function getvalue($array, $key)
{
return $array[$key];
}
Edit: As of PHP 5.4, you can index array elements directly from function expressions, current($arr)['item'].
Have you tried using one of the iterator classes yet? There might be something in there that does exactly what you want. If not, you can likely get what you want by extending the ArrayObject class.
This function might be a bit lenghty but I use it all the time, specially in scenarious like:
if (array_key_exists('user', $_SESSION) === true)
{
if (array_key_exists('level', $_SESSION['user']) === true)
{
$value = $_SESSION['user']['level'];
}
else
{
$value = 'DEFAULT VALUE IF NOT EXISTS';
}
}
else
{
$value = 'DEFAULT VALUE IF NOT EXISTS';
}
Turns to this:
Value($_SESSION, array('user', 'level'), 'DEFAULT VALUE IF NOT EXISTS');
Here is the function:
function Value($array, $key = 0, $default = false)
{
if (is_array($array) === true)
{
if (is_array($key) === true)
{
foreach ($key as $value)
{
if (array_key_exists($value, $array) === true)
{
$array = $array[$value];
}
else
{
return $default;
}
}
return $array;
}
else if (array_key_exists($key, $array) === true)
{
return $array[$key];
}
}
return $default;
}
PS: You can also use unidimensional arrays, like this:
Value($_SERVER, 'REQUEST_METHOD', 'DEFAULT VALUE IF NOT EXISTS');
If this does not work, how is your multidimensional array composed? A var_dump() might help.
$subkey = 'B';
$arr = array(
$subkey => array(
'AB' => 'A1',
'AC' => 'A2'
)
);
echo current($arr[$subkey]);
next($arr[$subkey]);
echo current($arr[$subkey]);
I often use
foreach ($arr as $key=>$val) {
$val['item'] /*$val is the value of the array*/
$key /*$key is the key used */
}
instead of
next($arr)/current($arr)