更改多维数组php的值 [英] Changing values of multidimensional array php

问题描述

这是我第一次在 php 中使用多维数组.我需要更改每个子数组中的第二个数字.

Its my first time working with multidimensional arrays in php. I need to change the second number in each sub array.

我想要的是检查数组中的 Id 是否与数据库中的 Id 匹配.当两者匹配时，我想通过向其添加一个数字来更改子数组中的第二个条目.如果查询中的 Id 与列表中的任何内容都不匹配，我希望将一个新的子数组推送到具有 Id 和 points_description 值的数组末尾.

What I want is to check if the Id in the array matches the Id from the database. When the two match I want to change the 2nd entry in the sub array by adding a number to it. If the Id from the query does not match anything in the list I want a new sub array to be pushed to the end of the array with the values of Id and points_description.

此外，如果有帮助，我的程序现在确实会找到匹配项.唯一的问题是，它不会更新二维数组.

Also, if its helpful, my program right now does find the matches. The only thing is, it does not update the 2D array.

$array = array(array());
while ($row_description = mysqli_fetch_array($query_description)) {
    $check = 1;
    $is_match = 0;

    foreach ($array as $i) {    
        foreach ($i as $value) {  
            if ($check == 1) {
                if ($row_description['Id'] == $value) {
                    //$array[$i] += $points_description;
                    $is_match = 1;
                }
             }

            $check++;
            $check %= 2; //toggle between check and points
        }
    }

    if ($is_match == 0) {
        array_push($array, array($row_description['Id'], $points_description));
    }
}

我觉得我这样做太错误了.我只想遍历我的二维数组并每隔一个值更改一次.预期的输出应该是所有 Id 及其对应点值的打印我希望这足够有帮助.

I feel like Im doing this so wrong. I just want to go through my 2D array and change every second value. The expected output should be a print out of all the Ids and their corresponding point value I hope this is helpful enough.

示例:$row_description['Id'] = 2 和 $array = array(array(2,1), array(5,1), array(6,1))

Example: $row_description['Id'] = 2 and $array = array(array(2,1), array(5,1) , array(6,1))

输出应该是 $array = array(array(2,4), array(5,1), array(6,1))

output should be $array = array(array(2,4), array(5,1) , array(6,1))

如果 $row_description['Id'] = 3 且 $array = array(array(2,1), array(5,1), array(6,1))

if $row_description['Id'] = 3 and $array = array(array(2,1), array(5,1) , array(6,1))

输出应该是 $array = array(array(2,4), array(5,1) , array(6,1),array(3,3))

output should be $array = array(array(2,4), array(5,1) , array(6,1),array(3,3))

推荐答案

默认情况下，当您在 foreach 中使用数组时，PHP 将复制一个数组.为了防止 PHP 创建此副本，您需要使用 &

By default PHP will copy an array when you use it in a foreach. To prevent PHP from creating this copy you need to use to reference the value with &

简单例子:

<?php

$arrFoo = [1, 2, 3, 4, 5,];
$arrBar = [3, 6, 9,];

默认 PHP 行为:复制

foreach($arrFoo as $value_foo) {
    foreach($arrBar as $value_bar) {
        $value_foo *= $value_bar;
    }   
}


var_dump($arrFoo);
/* Output :
array(5) {
  [0]=>
  int(1)
  [1]=>
  int(2)
  [2]=>
  int(3)
  [3]=>
  int(4)
  [4]=>
  int(5)

}
*/

ByReference : 不要创建副本 :

foreach($arrFoo as &$value_foo) {
    foreach($arrBar as $value_bar) {
        $value_foo *= $value_bar;
    }   
}

var_dump($arrFoo);
/* Output :
array(5) {
  [0]=>
  int(162)
  [1]=>
  int(324)
  [2]=>
  int(486)
  [3]=>
  int(648)
  [4]=>
  &int(810)
}

*/

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