How to append one array to another without comparing their keys?
$a = array( 'a', 'b' );
$b = array( 'c', 'd' );
At the end it should be: Array( [0]=>a [1]=>b [2]=>c [3]=>d ) If I use something like [] or array_push, it will cause one of these results:
Array( [0]=>a [1]=>b [2]=>Array( [0]=>c [1]=>d ) )
//or
Array( [0]=>c [1]=>d )
It just should be something, doing this, but in a more elegant way:
foreach ( $b AS $var )
$a[] = $var;
array_merge is the elegant way:
$a = array('a', 'b');
$b = array('c', 'd');
$merge = array_merge($a, $b);
// $merge is now equals to array('a','b','c','d');
Doing something like:
$merge = $a + $b;
// $merge now equals array('a','b')
Will not work, because the + operator does not actually merge them. If they $a has the same keys as $b, it won't do anything.
How about this:
$appended = $a + $b;
Why not use
$appended = array_merge($a,$b);
Why don't you want to use this, the correct, built-in method.
<?php
// Example 1 [Merging associative arrays. When two or more arrays have same key
// then the last array key value overrides the others one]
$array1 = array("a" => "JAVA", "b" => "ASP");
$array2 = array("c" => "C", "b" => "PHP");
echo " <br> Example 1 Output: <br>";
print_r(array_merge($array1,$array2));
// Example 2 [When you want to merge arrays having integer keys and
//want to reset integer keys to start from 0 then use array_merge() function]
$array3 =array(5 => "CSS",6 => "CSS3");
$array4 =array(8 => "JAVASCRIPT",9 => "HTML");
echo " <br> Example 2 Output: <br>";
print_r(array_merge($array3,$array4));
// Example 3 [When you want to merge arrays having integer keys and
// want to retain integer keys as it is then use PLUS (+) operator to merge arrays]
$array5 =array(5 => "CSS",6 => "CSS3");
$array6 =array(8 => "JAVASCRIPT",9 => "HTML");
echo " <br> Example 3 Output: <br>";
print_r($array5+$array6);
// Example 4 [When single array pass to array_merge having integer keys
// then the array return by array_merge have integer keys starting from 0]
$array7 =array(3 => "CSS",4 => "CSS3");
echo " <br> Example 4 Output: <br>";
print_r(array_merge($array7));
?>
Output:
Example 1 Output:
Array
(
[a] => JAVA
[b] => PHP
[c] => C
)
Example 2 Output:
Array
(
[0] => CSS
[1] => CSS3
[2] => JAVASCRIPT
[3] => HTML
)
Example 3 Output:
Array
(
[5] => CSS
[6] => CSS3
[8] => JAVASCRIPT
[9] => HTML
)
Example 4 Output:
Array
(
[0] => CSS
[1] => CSS3
)
It's a pretty old post, but I want to add something about appending one array to another:
If
you can use array functions like this:
array_merge(array_values($array), array_values($appendArray));
array_merge doesn't merge numeric keys so it appends all values of $appendArray. While using native php functions instead of a foreach-loop, it should be faster on arrays with a lot of elements.
Another way to do this in PHP 5.6+ would be to use the ... token
$a = array('a', 'b');
$b = array('c', 'd');
array_push($a, ...$b);
// $a is now equals to array('a','b','c','d');
This will also work with any Traversable
$a = array('a', 'b');
$b = new ArrayIterator(array('c', 'd'));
array_push($a, ...$b);
// $a is now equals to array('a','b','c','d');
A warning though, this will cause a fatal error if array $b is empty
For big array, is better to concatenate without array_merge, for avoid a memory copy.
$array1 = array_fill(0,50000,'aa');
$array2 = array_fill(0,100,'bb');
// Test 1 (array_merge)
$start = microtime(true);
$r1 = array_merge($array1, $array2);
echo sprintf("Test 1: %.06f
", microtime(true) - $start);
// Test2 (avoid copy)
$start = microtime(true);
foreach ($array2 as $v) {
$array1[] = $v;
}
echo sprintf("Test 2: %.06f
", microtime(true) - $start);
// Test 1: 0.004963
// Test 2: 0.000038
Following on from answer's by bstoney and Snark I did some tests on the various methods:
$array1 = array_fill(0,50000,'aa');
$array2 = array_fill(0,50000,'bb');
// Test 1 (array_merge)
$start = microtime(true);
$array1 = array_merge($array1, $array2);
echo sprintf("Test 1: %.06f
", microtime(true) - $start);
// Test2 (foreach)
$start = microtime(true);
foreach ($array2 as $v) {
$array1[] = $v;
}
echo sprintf("Test 2: %.06f
", microtime(true) - $start);
// Test 3 (... token)
// PHP 5.6+ and produces error if $array2 is empty
$start = microtime(true);
array_push($array1, ...$array2);
echo sprintf("Test 3: %.06f
", microtime(true) - $start);
Which produces:
Test 1: 0.008392
Test 2: 0.004626
Test 3: 0.003574
I believe as of PHP 7, method 3 is a significantly better alternative due to the way foreach loops now act, which is to make a copy of the array being iterated over.
Whilst method 3 isn't strictly an answer to the criteria of 'not array_push' in the question, it is one line and the most high performance in all respects, I think the question was asked before the ... syntax was an option.
if you want to merge empty array with existing new value. You must initialize it first.
$products = array();
//just example
for($brand_id=1;$brand_id<=3;$brand_id++){
array_merge($products,getByBrand($brand_id));
}
// it will create empty array
print_r($a);
//check if array of products is empty
for($brand_id=1;$brand_id<=3;$brand_id++){
if(empty($products)){
$products = getByBrand($brand_id);
}else{
array_merge($products,getByBrand($brand_id));
}
}
// it will create array of products
Hope its help.
Before PHP7 you can use:
array_splice($a, count($a), 0, $b);
array_splice() operates with reference to array (1st argument) and puts array (4th argument) values in place of list of values started from 2nd argument and number of 3rd argument. When we set 2nd argument as end of source array and 3rd as zero we append 4th argument values to 1st argument
foreach loop is faster than array_merge to append values to an existing array, so choose the loop instead if you want to add an array to the end of another.
// Create an array of arrays
$chars = [];
for ($i = 0; $i < 15000; $i++) {
$chars[] = array_fill(0, 10, 'a');
}
// test array_merge
$new = [];
$start = microtime(TRUE);
foreach ($chars as $splitArray) {
$new = array_merge($new, $splitArray);
}
echo microtime(true) - $start; // => 14.61776 sec
// test foreach
$new = [];
$start = microtime(TRUE);
foreach ($chars as $splitArray) {
foreach ($splitArray as $value) {
$new[] = $value;
}
}
echo microtime(true) - $start; // => 0.00900101 sec
// ==> 1600 times faster