PHP：包装每组 3 个元素

Question

我想弄清楚如何编写一个循环来包装每组 3 个元素。然而，对于最后一次迭代，它应该包装剩下的任何东西（无论是一个、两个还是三个元素）

所以基本上是这种模式：

div
do stuff
do stuff
do stuff
end-div
div
do stuff
do stuff
do stuff
end-div
div
do stuff
do stuff
do stuff
end-div
div
do stuff
end-div

这是我目前所处的位置：

<?php

  $counter = 0;

  for ($i = 1; $i <= 10; $i++) {

    if (($counter + 1) % 3 == 0) {
      echo 'div <br />';
    }
    echo 'do stuff <br />';
    if (($counter + 1) % 3 == 0) {
      echo 'end-div <br />';
    }

    $counter ++;
  }

?>

这给了我以下信息：

do stuff 
do stuff 
div 
do stuff 
end-div 
do stuff 
do stuff 
div 
do stuff 
end-div 
do stuff 
do stuff 
div 
do stuff 
end-div 
do stuff

谁能看出我错在哪里？

Answer 1

无需使用单独的 $counter 变量，在 for 循环本身中使用 $i 变量。

echo 'div <br />';
for ($i = 0; $i < 10; $i++) {
    if($i != 0 && $i % 3 == 0)
        echo 'end-div <br /> div <br />';
    echo 'do stuff <br />';
}
echo 'end-div';

Answer 2

也就是说每组三项前写div，每组三项后写end-div：

// $counter always tells the number of processed items
$counter = 0;

for ($i = 1; $i <= 10; $i++) {
    // before a group of three, $counter is a multiple of three
    if ($counter % 3 == 0) {
        echo 'div <br />';
    }

    // process the item then count it
    echo 'do stuff <br />';
    $counter ++;

    // after a group of three, $counter is a multiple of three
    if ($counter % 3 == 0) {
        echo 'end-div <br />';
    }
}

// close the last group if it is not complete
if ($counter % 3 != 0) {
    echo 'end-div <br />';
}

检查一下online。

Answer 3

我就是这样解决问题的

$total_items = 11;



for( $i = 0; $i < $total_items; $i ++ ){
    // get the starting element
    // the starting element will have ($i + 1 ) % 3 = 1
    // all starting elements in the group will have a  modulus of 1 when divided by 3


    if( ( $i + 1 ) % 3 == 1  ){
        echo "div <br />";
    }

    echo "do stuff <br />";

    // the group will either end where ($i + 1 ) % 3 = 0
    // or at the end of the count 
    // if total items are 2 then it will end at 2

    if( ( $i + 1 ) % 3 == 0 || ( $i + 1 )  == $total_items ){
        echo "end-div <br /><br />";
    }

}

我运行我的代码使用w3schools PHP编译器，请看截图

PHP：包装每组 3 个元素

PHP: wrapping each group of 3 elements

php

loops

for-loop

iteration

modulus