If I assign values to array like this:
$foo[0] = 2;
$foo[1] = 3;
print_r($foo);
I get:
Array
(
[0] => 2
[1] => 3
)
But if I do:
$foo[1] = 3;
$foo[0] = 2 ;
print_r($foo);
I get:
Array
(
[1] => 3
[0] => 2
)
As you can see first goes array with index 1 and it confuses me, is it possible to make that it would start from 0
If you interested, I assign value to array with index 1 because I need to use that value for calculating array with index 0
try to use ksort();. It sorts your keys ascending
<?php
$foo[1] = 3;
$foo[0] = 2 ;
ksort($foo);
print_r($foo);
results in
Array (
[0] => 2
[1] => 3
)
demo
Try ksort()
The reason it is like this in PHP, is because arrays are a bit different from arrays in other languages. Arrays in PHP are somewhat similar to HashMaps in Java and Dictionaries in C#, although still a bit different.
You can also add
$foo[0] = '';
,before you add any value to $foo[1]
Related
I want to need multiple array combaine in one array
I have array
array(
0=> test 1
)
array(
0=> test 2
)
array(
0=> test 3
)
I need expected output
`array(
0=>Test1
1=>Test2
2=>test3
)`
You can use the array_merge() for this. The array_merge() function merges one or more arrays into one array.If two or more array elements have the same key, the last one overrides the others.
Syntax:
array_merge(array ...$arrays): array
Example:
$a1=array("red","green");
$a2=array("blue","yellow");
print_r(array_merge($a1,$a2));
Result:
Array ( [0] => red [1] => green [2] => blue [3] => yellow )
You can check more here.
$a = array('test_1');
$b = array('test_2');
$c = array('test_3');
print_r(array_merge($a,$b,$c));
O/P - Array ( [0] => test_1 [1] => test_2 [2] => test_3 )
Hope you are doing well and good.
So, as per your requirement i found solution to get result.
$array1 = [0 => "Test 1"]; $array2 = [0 => "Test 2"]; $array3 = [0 => "Test 3"];
print_r(array_merge($array1,$array2,$array3));
In the above example you have to merge the n number of array with single array, so for that you need to use array function which is array_merge(array ...$array).
What is array_merge()?
The array_merge() function merges one or more arrays into one array.
Tip: You can assign one array to the function, or as many as you like.
Note: If two or more array elements have the same key, the last one overrides the others.
I'm building an array piece by piece following a specific pattern.
For example, I have this string <val0=0, val1=<val2=2, val3=<val4=4>>, val5=5> and I need to translate it to an associative array. So every time I find < I have to create a new array and store the following elements until the next >.
The string above should result in something like this:
Array
(
[val0] => 0
[val1] => Array
(
[val2] => 2
[val3] => Array
(
[val4] => 4
)
)
[val5] => 5
)
Everything is working fine for non-multidimensional arrays using str_split to break the string in pieces and iterating over them in a for loop but I'm having difficulties to find a workaround every time there is a nesting array in the string.
What I need is a way to have a pointer to the last created array inside the main array.
Is there a way to store an array pointer reference in a variable so I could do this:
print_r($MULTIARRAY['val1']['val3']);
// prints: array()
$pointer = pointer($MULTIARRAY['val1']['val3']);
$pointer[] = 'AAA';
$pointer[] = 'BBB';
print_r($MULTIARRAY['val1']['val3']);
// prints: array(
// [0] => AAA
// [1] => BBB
//)
Here you go, it's called reference
$a[1][22] = array();
$pointer = &$a[1][22];
$pointer[] = 3;
$pointer[] = 4;
print_r($a);
i have two array and i want to make unique array with single array
for example i have $a=array(3); and $b=array(1,2,3) so i want $c=array(1,2,3)
i made a code like:
$a=array(3);
$b=explode(',','1,2,3');
$ab=$a+$b;
$c=array_unique ($ab);
print_r($c);
it gives me Array ( [0] => 3 [1] => 2 )
but i want to Array ( [0] => 1 [1] => 2 [2] => 3 )
$a = array(1,2,3,4,5,6);
$b = array(6,7,8,2,3);
$c = array_merge($a, $b);
$c = array_unique($c);
The operation
$ab = $a + $b
Is giving you a result you did not expect. The reason for this behaviour has been explained previously at PHP: Adding arrays together
$ab is Array ( [0] => 3 [1] => 2 [2] => 3 )
The + operator appends elements of remaining keys from the right
handed array to the left handed, whereas duplicated keys are NOT
overwritten.
array_merge provides a more intuitive behaviour.
Array merge, man. Array merge.
Anyway, as this answer for similar question ( https://stackoverflow.com/a/2811849/223668 ) tells us:
The + operator appends elements of remaining keys from the right handed array to the left handed, whereas duplicated keys are NOT overwritten.
If you have numeric keys (as in standard tables), they are for for sure duplicate in both arrays and the result is far from desired.
So the code should look like that:
$c = array_unique(array_merge($a, $b));
You need to use this array_merge to concat two array.
http://www.php.net/manual/en/function.array-merge.php
not
$ab = $a + $b
So here's what I see this code doing:
An array is made
A loop iterates 10 times
A new array is created
A reference to this new array is saved in the first array
10 arrays now reside in the original array with values 0, 1, 2, 3...
What really happens:
WTF?
Code:
<?php
header('Content-type: text/plain');
$arrays = array();
foreach(range(0, 10) as $i)
{
$arr = array();
$arr[0] = $i;
$arrays[] = &$arr;
}
print_r($arrays);
Output:
Array
(
[0] => Array
(
[0] => 10
)
[1] => Array
(
[0] => 10
)
[2] => Array
(
[0] => 10
)
[3] => Array
(
[0] => 10
)
[4] => Array
(
[0] => 10
)
[5] => Array
(
[0] => 10
)
[6] => Array
(
[0] => 10
)
[7] => Array
(
[0] => 10
)
[8] => Array
(
[0] => 10
)
[9] => Array
(
[0] => 10
)
[10] => Array
(
[0] => 10
)
)
I would like to know exactly why apparently only the 10th array is referred to ten times, instead of every instance of the arrays being referred to one each.
Also if somebody who isn't just thinking WTF (like me) would like to edit the title, feel free to do so.
The line
$arr = array();
does not create a new array but rather assigns an empty array to the already existing reference.
If you want the variable name to "point" to a different array in memory, you have to unset() (or "disconnect") it first before assigning an empty array to it:
foreach(range(0, 10) as $i)
{
unset($arr);
$arr = array();
$arr[0] = $i;
$arrays[] = &$arr;
}
This is because the only operations that can make a variable point to something else is the reference assignment (=&) and the unset().
What happens here is that by inserting a reference to $arr inside $arrays, you are effectively adding the exact same array 10 times -- and each reference to the array has the value last assigned to it (i.e. the one produced when $i is 10).
It's not clear what you intend to achieve by inserting a reference in each iteration -- either removing the & or putting unset($arr) at the beginning of the loop would give you the expected behavior. What are you trying to accomplish?
Think about it this way. You do $arrays[] = &$arr; 10 times. This stores a reference to the local variable $arr 10 times. Since it's the same variable (the variable's scope is the entire function), it stores the same reference all 10 times. Thus, why should you expect the 10 elements to be different?
The reference you are storing has nothing to do with the value of $arr; it just has to do with the variable $arr. When you print the reference it prints the value of $arr at that time.
It's because you're storing a reference to the array that $arr points to in the array. And you keep overwriting that array with the latest number. All references in $arr will point to the same array in the end.
I don't know what you expect to get out of this in the end, but getting rid of & should fix this behavior.
I have an array that contains entries that themselves contain two types of entries.
For simplicity sake, let's say that the entries are like this:
a|1
b|4
a|2
c|5
b|3
etc.
In fact they represent categories and subcategories in my database.
I will use explode to break these entries into letters and digits.
The question is: I want to group them by category.
What's the easiest way to create a multilevel array, which could be sorted by letters:
a|1
a|2
b|4
b|3
c|5
?
How about something like this?
$input = array('a|1','b|4','a|2','c|5','b|3');
$output = array();
foreach($input as $i){
list($key,$val) = explode("|",$i);
$output[$key][] = $val;
}
Output:
Array
(
[a] => Array
(
[0] => 1
[1] => 2
)
[b] => Array
(
[0] => 4
[1] => 3
)
[c] => Array
(
[0] => 5
)
)
<?php
$your_array = array();
$your_array[a] = array('1','2','3');
$your_array[b] = array('4','5','6');
print_r($your_array);
?>
I take it that your entries are strings (relying on the fact that you want to use explode() on them).
If so you can simply sort the array by using sort($array), and then iterate on that array and explode the values and put them in another array, which will be sorted by the previous array's order.