Is there a way in php to remove elements in an array and then reindex the remaining elements? For example, here is what I want to do. In an array,
$a = array("a","b","c");
I want to delete element "b", I used unset() to do that leaving the array like ("a",null,"c"). What I really want is make the array ("a","c") after deleting "b". How can I do that? Thanks!
unset does not create null elements in your array. The array will be one element smaller than before.
If you want to reindex the array after removing an element, use $array = array_values($array);.
do you want to do something like
$new_array = array_filter($a)
? You can read about array filter function and take a look at the case without callback parameter (as in my example)
unset($a[1]);
$a = array_values($a);
Related
Which one would you use?
Basically I only want to get the 1st element from a array, that's it.
Well, they do different things.
array_shift($arr) takes the first element out of the array, and gives it to you.
$arr[0] just gives it to you... if the array has numeric keys.
An alternative that works for associative arrays too is reset($arr). This does move the array's internal pointer, but unless you're using those functions this is unlikely to affect you.
array_shift will actually remove the specified value from the array. Do not use it unless you really want to reduce the array!
See here: http://php.net/manual/en/function.array-shift.php
You would use $arr[ 0 ]; array_shift removes the first element from the array.
EDIT
This answer is actually somewhere between incomplete and plain out wrong but, because the comments of the two jon's I think that it should actually stay up so that others can see that discourse.
The right answer:
reset is the method to return the first defined index of the array. Even in non-associative arrays, this may not be the 0 index.
array_shift will remove and return the value which is found at reset
The OP made the assumption that $arr[0] is the first index is not accurate in that particular context.
$arr[0] only works if the array as numerical keys.
array_shift removes the element from the array and it modifies the array itself.
If you are not sure what the first key is , and you do not want to remove it from the array, you could use:
<?php
foreach($arr $k=>$v){
$value = $v;
break;
}
or even better:
<?php
reset($arr);
$value = current($arr);
If you have an associative Array you can also use reset($arr): It returns the first Element (doesn't remove), and sets the array pointer to this element.
But the fastest way is $arr[0].
Do you want to modify the arr array also? array_shift removes the first element of the array and returns it, thus the array has changed. $arr[0] merely gives you the first element.
I would use $arr[0] unless I explicitly wanted to modify the array. You may add code later to use the arr array and forget that it was modified.
given what you need, $arr[0] is preferrable, because it's faster. array_shift is used in other situations.
arrshift is more reliable and will always return the first element in the array, but this also modifies the array by removing that element.
arr[0] will fail if your array doesn't start at the 0 index, but leaves the array itself alone.
A more convoluted but reliable method is:
$keys = array_keys($arr);
$first = $arr[$keys[0]];
with array_shif you have two operations:
retrive the firs element
shift the array
if you access by index, actually you have only one operation.
If you want the first element of an array, use $arr[0] form. Advantages - Simplicity, Readability and Maintainability. Keep things straight forward.
Edit: Use index 0 only if you know that the array has default keys starting from 0.
If you don't want to change the array in question, use $arr[0] (which merely gets the first element), otherwise if you want to remove the first element of $arr from $arr, use array_shift($arr).
For example:
$arr=array(3,-6,2);
$foo=$arr[0]; //$foo==3 and $arr==array(3,-6,2).
$bar=array_shift($arr); //$bar==3 and $arr==array(-6,2).
ETA: As others have pointed out, be sure that your array isn't an associative array (ie the keys are 0,1,...,(sizeof($arr)-1)), otherwise this probably won't work.
I have two arrays with the same keys but different values. I need to merge it but if the values are the same leave only one of this
$array1 = array('firstname'=> $may_name, 'lastname'=>$my_last_name, 'address'=>$addres_1);
$array2 = array('firstname'=> $may_name, 'lastname'=>$my_last_name, 'address'=>$addres_2);
I need to get:
$array_result = array('firstname'=> $may_name, 'lastname'=>$my_last_name, 'address'=>$addres_1, 'address'=>$addres_2);
can anybody help to solve this?
array_merge does not work for me..
First you need to merge 2 arrays, using array_merge() function. then get the unique elements from the array using array_unique() function will get you the result
var_dump(array_unique(array_merge($array1, $array2)));
Edit
If the input arrays have the same string keys, then the later value for that key will overwrite the previous one. If, however, the arrays contain numeric keys, the later value will not overwrite the original value, but will be appended.
php doc
Thanks #Marco
I'm trying to find out if there's a way of removing an array element and at the same time storing that value in a variable.
i.e.
$array = [
'foo' => 'a',
'bar' => 'b'
];
// Perform the following with one action?
$var = $array['foo'];
unset($array['foo']);
Edit: I mean if it can be done without a custom function.
There is but it's slow and ugly.
$var = array_splice($array, array_search('foo', array_keys($array)), 1)['foo'];
I'd stick with the 2-liner.
It can be done under certain circumstances.
There are two functions which do what sort of what you want.
array_pop($stack);
array_shift($stack);
But array_pop gets and removes only the last element and array_push the first of the array which can lead to unexxpected behaviour of your code if you are using an associative array.
However if you can restructure your array to fit for these functions without increasing the complexity (which would make this whole thing pointless) it can be done.
The two links for the functions are:
array_pop
array_shift
An entire reference of the array function can be found here. Maybe you find something that serves you the way you need it to:
Array functions reference
I have two associative arrays, and I need to merge it into one array, without an element from first array.
Now it looks like that:
$result = array_merge(getFirstArray(), getSecondArray());
What's the best way to do it?
and I need to merge it into one array, without an element from first array.
Then remove it. Before or after merge.
If you don't want the element in the first array and you know which one it is, then just remove it before the merge:
$array1 = getFirstArray();
unset($array1['element1']); // or $array1[0] or whatever the index is;
$result = array_merge($array1, getSecondArray());
$result = array_filter(getFirstArray(),
array_merge(getFirstArray(), getSecondArray());
Which one would you use?
Basically I only want to get the 1st element from a array, that's it.
Well, they do different things.
array_shift($arr) takes the first element out of the array, and gives it to you.
$arr[0] just gives it to you... if the array has numeric keys.
An alternative that works for associative arrays too is reset($arr). This does move the array's internal pointer, but unless you're using those functions this is unlikely to affect you.
array_shift will actually remove the specified value from the array. Do not use it unless you really want to reduce the array!
See here: http://php.net/manual/en/function.array-shift.php
You would use $arr[ 0 ]; array_shift removes the first element from the array.
EDIT
This answer is actually somewhere between incomplete and plain out wrong but, because the comments of the two jon's I think that it should actually stay up so that others can see that discourse.
The right answer:
reset is the method to return the first defined index of the array. Even in non-associative arrays, this may not be the 0 index.
array_shift will remove and return the value which is found at reset
The OP made the assumption that $arr[0] is the first index is not accurate in that particular context.
$arr[0] only works if the array as numerical keys.
array_shift removes the element from the array and it modifies the array itself.
If you are not sure what the first key is , and you do not want to remove it from the array, you could use:
<?php
foreach($arr $k=>$v){
$value = $v;
break;
}
or even better:
<?php
reset($arr);
$value = current($arr);
If you have an associative Array you can also use reset($arr): It returns the first Element (doesn't remove), and sets the array pointer to this element.
But the fastest way is $arr[0].
Do you want to modify the arr array also? array_shift removes the first element of the array and returns it, thus the array has changed. $arr[0] merely gives you the first element.
I would use $arr[0] unless I explicitly wanted to modify the array. You may add code later to use the arr array and forget that it was modified.
given what you need, $arr[0] is preferrable, because it's faster. array_shift is used in other situations.
arrshift is more reliable and will always return the first element in the array, but this also modifies the array by removing that element.
arr[0] will fail if your array doesn't start at the 0 index, but leaves the array itself alone.
A more convoluted but reliable method is:
$keys = array_keys($arr);
$first = $arr[$keys[0]];
with array_shif you have two operations:
retrive the firs element
shift the array
if you access by index, actually you have only one operation.
If you want the first element of an array, use $arr[0] form. Advantages - Simplicity, Readability and Maintainability. Keep things straight forward.
Edit: Use index 0 only if you know that the array has default keys starting from 0.
If you don't want to change the array in question, use $arr[0] (which merely gets the first element), otherwise if you want to remove the first element of $arr from $arr, use array_shift($arr).
For example:
$arr=array(3,-6,2);
$foo=$arr[0]; //$foo==3 and $arr==array(3,-6,2).
$bar=array_shift($arr); //$bar==3 and $arr==array(-6,2).
ETA: As others have pointed out, be sure that your array isn't an associative array (ie the keys are 0,1,...,(sizeof($arr)-1)), otherwise this probably won't work.