PHP: How to delete all array elements after an index [duplicate]

问题

Is it possible to delete all array elements after an index?

$myArrayInit = array(1=>red, 30=>orange, 25=>velvet, 45=>pink);

now some "magic"

$myArray = delIndex(30, $myArrayInit);

to get

$myArray = array(1=>red, 30=>orange);

due to the keys in $myArray are not successive, I don't see a chance for array_slice()

Please note : Keys have to be preserved! + I do only know the Offset Key!!

回答1:

Without making use of loops.

<?php
    $myArrayInit = [1 => 'red', 30 => 'orange', 25 => 'velvet', 45 => 'pink']; //<-- Your actual array
    $offsetKey = 25; //<--- The offset you need to grab

    //Lets do the code....
    $n = array_keys($myArrayInit); //<---- Grab all the keys of your actual array and put in another array
    $count = array_search($offsetKey, $n); //<--- Returns the position of the offset from this array using search
    $new_arr = array_slice($myArrayInit, 0, $count + 1, true);//<--- Slice it with the 0 index as start and position+1 as the length parameter.
    print_r($new_arr);

Output :

Array
(
    [1] => red
    [30] => orange
    [25] => velvet
)

回答2:

Try

$arr = array(1=>red, 30=>orange, 25=>velvet, 45=>pink);
$pos = array_search('30', array_keys($arr));
$arr= array_slice($arr,0,$pos+1,true);
echo "<pre>";
print_r($arr);

See demo

回答3:

I'd iterate over the array up until you reach the key you want to truncate the array thereafter, and add those items to a new - temporary array, then set the existing array to null, then assign the temp array to the existing array.

回答4:

This uses a flag value to determine your limit:

$myArrayInit = array(1=>'red', 30=>'orange', 25=>'velvet', 45=>'pink');

$new_array = delIndex(30,$myArrayInit);

function delIndex($limit,$array){

    $limit_reached=false;

    foreach($array as $ind=>$val){

        if($limit_reached==true){
            unset($array[$ind]);
        }
        if($ind==$limit){
            $limit_reached=true;
        }

    }
    return $array;
}
print_r($new_array);

回答5:

Try this:

function delIndex($afterIndex, $array){
    $flag = false;
    foreach($array as $key=>$val){
        if($flag == true)
            unset($array[$key]);
        if($key == $afterIndex)
             $flag = true; 
    }
    return $array;
}

This code is not tested

来源：https://stackoverflow.com/questions/21851127/php-how-to-delete-all-array-elements-after-an-index

标签

php

arrays

function

output

associative-array