PHP foreach loop show each list item while only showing list name once

问题

Please compare the CURRENT and DESIRED results below to see what I'm trying to do.

$arr=array(
array('list_name'=>'Food', 'list_item'=>'bread'),
array('list_name'=>'Food', 'list_item'=>'meat'),
array('list_name'=>'Drinks', 'list_item'=>'water'),
array('list_name'=>'Drinks', 'list_item'=>'milk')
);

foreach($arr as $row){   
  echo $row['list_name'].'<br>'; 
  echo $row['list_item'].'<br>';
  echo '<br>___<br>';
}

CURRENT RESULT

Food
bread

___
Food
meat

___
Drinks
water

___
Drinks
milk

___

DESIRED RESULT

Food
1.bread
2.meat
___

Drinks
1.water
2.milk
___

UPDATE

More complex, yet more generalizable example:

$arr=array(
array('list_name'=>'Food', 'list_item1'=>'bread', 'list_item2' => 2001),
array('list_name'=>'Food', 'list_item1'=>'meat', 'list_item2' => 2002),
array('list_name'=>'Drinks', 'list_item1'=>'water', 'list_item2' => 2003),
array('list_name'=>'Drinks', 'list_item1'=>'milk', 'list_item2' => 2004)
);

DESIRED RESULT

Food
1.bread, 2001
2.meat, 2002
___

Drinks
1.water, 2003
2.milk, 2004
___

回答1:

You could iterate over the array and add the item data to a new array (one for each list_name).

For example:

$new_array = array();

foreach ($arr as $row)
{
  $new_array[$row['list_name']][] = $row['list_item'];
}

foreach ($new_array as $name => $items)
{

  echo $name . '<br>'; 

  foreach ($items as $index => $item)
  {
    echo ($index + 1) . '. ' . $item . '<br>';
  }

  echo '___<br>';

}

With your update:

$new_array = array();

foreach ($arr as $row)
{

  $name = $row['list_name'];

  unset($row['list_name']);

  $new_array[$name][] = $row;

}

foreach ($new_array as $name => $items)
{

  echo $name . '<br>'; 

  foreach ($items as $index => $item)
  {
    echo ($index + 1) . '. ' . implode(', ', $item) . '<br>';
  }

  echo '___<br>';

}

回答2:

$arr=array(
array('list_name'=>'Food', 'list_item'=>'bread'),
array('list_name'=>'Food', 'list_item'=>'meat'),
array('list_name'=>'Drinks', 'list_item'=>'water'),
array('list_name'=>'Drinks', 'list_item'=>'milk')
);

$names = array();

foreach ( $arr as $item){
    $name = $item['list_name'];
    if(!in_array($name, $names)){
        $names[] = $name;
        echo $name ."<BR>";
    }
    echo $item['list_item']."<BR>";
}

回答3:

One common recipe for this is to store the current heading/section into a variable as you loop over the list. Then each time you encounter a new heading, you echo that heading, and re-start your numbering (or close your HTML <ol> tag, etc).

$current_section = NULL;
foreach ( $arr as $row )
{
    if ( $current_section != $row['list_name'] )
    {
        // Begin new section
        echo $row['list_name'];
        // Remember current section
        $current_section != $row['list_name'];
    }

    // Output current item
    echo $row['list_item'];
}

Note that this approach will only work if your list is sorted such that all "food" items come together, then all "drinks", etc.

Otherwise, you can use the alternative approach of re-structuring your array so that there is a sub-array for each section, and then using a pair of nested loops:

$new_array = array();
foreach ($arr as $row)
{
    $new_array[$row['list_name']][] = $row['list_item'];
}

foreach ( $new_array as $section_name => $items )
{
    echo $section_name;
    foreach ( $items as $row )
    {
        echo $row;
    }
}

回答4:

Ok, I made a mistake earlier but I tested this and it does work.

<?php
$food = array('bread', 'meat');
$drink = array('water', 'milk');

$object = array('food' => $food, 'drink' => $drink);

foreach($object as $row){   
  echo $row[0].'<br>'; 
  echo $row[1].'<br>';
  echo '<br>___<br>';
}
?>

来源：https://stackoverflow.com/questions/15178829/php-foreach-loop-show-each-list-item-while-only-showing-list-name-once

标签

php

multidimensional-array

foreach