Foreach key index php

Как получить текущий индекс массива в цикле foreach?

Если вы хотите узнать, например, если это первая, вторая или итерация цикла, это ваш единственный вариант:

Конечно, это не означает, что $val == $arr[$i] потому что массив может быть ассоциативным массивом.

Это самый исчерпывающий ответ до сих пор и избавляет от необходимости плавающей переменной $i . Это комбо ответов Кипа и Гнарфа.

$array = array( 'cat' => 'meow', 'dog' => 'woof', 'cow' => 'moo', 'computer' => 'beep' ); foreach( array_keys( $array ) as $index=>$key ) < // display the current index + key + value echo $index . ':' . $key . $array[$key]; // first index if ( $index == 0 ) < echo ' -- This is the first element in the associative array'; >// last index if ( $index == count( $array ) - 1 ) < echo ' -- This is the last element in the associative array'; >echo '
'; > 

Надеюсь, это поможет кому-то.

$i = 0; foreach ($arr as $key => $val) < if ($i === 0) < // first index >// current index is $i $i++; > 

$ key – это индекс каждого элемента $ array

Вы можете получить значение индекса с помощью этого

Текущий индекс – это значение $key . И по другому вопросу вы также можете использовать:

для получения первого элемента любого массива, предполагая, что вы не используете функции next() , prev() или другие функции для изменения внутреннего указателя массива.

$key – это индекс для текущего элемента массива, а $val – значение этого элемента массива.

Первый элемент имеет индекс 0. Поэтому для доступа к нему используйте $arr[0]

Чтобы получить первый элемент массива, используйте этот

$firstFound = false; foreach($arr as $key=>$val) < if (!$firstFound) $first = $val; else $firstFound = true; // do whatever you want here >// now ($first) has the value of the first element in the array 

Вы можете получить первый элемент в функции array_keys() . Или array_search() ключи для «индекса» ключа. Если вы находитесь внутри цикла foreach , простой инкрементный счетчик (предложенный kip или cletus), вероятно, является вашим самым эффективным методом.

'something', 'test2'=>'something else'); $keys = array_keys($array); var_dump(array_search("test2", $keys)); // int(1) var_dump(array_search("test3", $keys)); // bool(false) 

так как это первый хит Google для этой проблемы:

function mb_tell(&$msg) < if(count($msg) == 0) < return 0; >//prev($msg); $kv = each($msg); if(!prev($msg)) < end($msg); print_r($kv); return ($kv[0]+1); >print_r($kv); return ($kv[0]); > 

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Foreach key index php

The foreach construct provides an easy way to iterate over arrays. foreach works only on arrays and objects, and will issue an error when you try to use it on a variable with a different data type or an uninitialized variable. There are two syntaxes:

foreach (iterable_expression as $value) statement foreach (iterable_expression as $key => $value) statement

The first form traverses the iterable given by iterable_expression . On each iteration, the value of the current element is assigned to $value .

The second form will additionally assign the current element’s key to the $key variable on each iteration.

Note that foreach does not modify the internal array pointer, which is used by functions such as current() and key() .

In order to be able to directly modify array elements within the loop precede $value with &. In that case the value will be assigned by reference.

$arr = array( 1 , 2 , 3 , 4 );
foreach ( $arr as & $value ) $value = $value * 2 ;
>
// $arr is now array(2, 4, 6, 8)
unset( $value ); // break the reference with the last element
?>

Reference of a $value and the last array element remain even after the foreach loop. It is recommended to destroy it by unset() . Otherwise you will experience the following behavior:

// without an unset($value), $value is still a reference to the last item: $arr[3]

foreach ( $arr as $key => $value ) // $arr[3] will be updated with each value from $arr.
echo » < $key >=> < $value >» ;
print_r ( $arr );
>
// . until ultimately the second-to-last value is copied onto the last value

// output:
// 0 => 2 Array ( [0] => 2, [1] => 4, [2] => 6, [3] => 2 )
// 1 => 4 Array ( [0] => 2, [1] => 4, [2] => 6, [3] => 4 )
// 2 => 6 Array ( [0] => 2, [1] => 4, [2] => 6, [3] => 6 )
// 3 => 6 Array ( [0] => 2, [1] => 4, [2] => 6, [3] => 6 )
?>

It is possible to iterate a constant array’s value by reference:

Note:

foreach does not support the ability to suppress error messages using @ .

Some more examples to demonstrate usage:

/* foreach example 1: value only */

foreach ( $a as $v ) echo «Current value of \$a: $v .\n» ;
>

/* foreach example 2: value (with its manual access notation printed for illustration) */

$i = 0 ; /* for illustrative purposes only */

foreach ( $a as $v ) echo «\$a[ $i ] => $v .\n» ;
$i ++;
>

/* foreach example 3: key and value */

$a = array(
«one» => 1 ,
«two» => 2 ,
«three» => 3 ,
«seventeen» => 17
);

foreach ( $a as $k => $v ) echo «\$a[ $k ] => $v .\n» ;
>

/* foreach example 4: multi-dimensional arrays */
$a = array();
$a [ 0 ][ 0 ] = «a» ;
$a [ 0 ][ 1 ] = «b» ;
$a [ 1 ][ 0 ] = «y» ;
$a [ 1 ][ 1 ] = «z» ;

foreach ( $a as $v1 ) foreach ( $v1 as $v2 ) echo » $v2 \n» ;
>
>

/* foreach example 5: dynamic arrays */

foreach (array( 1 , 2 , 3 , 4 , 5 ) as $v ) echo » $v \n» ;
>
?>

Unpacking nested arrays with list()

It is possible to iterate over an array of arrays and unpack the nested array into loop variables by providing a list() as the value.

foreach ( $array as list( $a , $b )) // $a contains the first element of the nested array,
// and $b contains the second element.
echo «A: $a ; B: $b \n» ;
>
?>

The above example will output:

You can provide fewer elements in the list() than there are in the nested array, in which case the leftover array values will be ignored:

foreach ( $array as list( $a )) // Note that there is no $b here.
echo » $a \n» ;
>
?>

The above example will output:

A notice will be generated if there aren’t enough array elements to fill the list() :

foreach ( $array as list( $a , $b , $c )) echo «A: $a ; B: $b ; C: $c \n» ;
>
?>

The above example will output:

Notice: Undefined offset: 2 in example.php on line 7 A: 1; B: 2; C: Notice: Undefined offset: 2 in example.php on line 7 A: 3; B: 4; C:

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How to Find the foreach Index with PHP

In this tutorial, we provide you with helpful methods to find the foreach index in PHP.

Below, you can find three options with proper examples.

Applying the key Variable

The key variable contains the index of every value inside the foreach loop. In PHP, the foreach loop is used like this:

 foreach ($arrayName as $value) < //code > ?>

The value variable contains the value of every element of the array. Here is an example:

 $array = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]; foreach ($array as $key => $value) < echo "The index is = " . $key . ", and value is = " . $value; echo "\n"; > ?>

Here, the key variable stores the index of the foreach loop. The variable value demonstrates the value of every element within the array.

The output will look as follows:

The index is = 0, and the value is = 1 The index is = 1, and the value is = 2 The index is = 2, and the value is = 3 The index is = 3, and the value is = 4 The index is = 4, and the value is = 5 The index is = 5, and the value is = 6 The index is = 6, and the value is = 7 The index is = 7, and the value is = 8 The index is = 8, and the value is = 9 The index is = 9, and the value is = 10

Applying the index Variable

The index variable is applied as an additional variable for demonstrating the index of the foreach loop in any iteration.

 // Declare an array $arr = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]; $index = 0; foreach ($arr as $key => $val) < echo "The index is $index"; $index++; echo "\n"; > ?>

It is essential to consider that the index variable should initially be initialized with a value. Afterwards, it increments any time the loop iterates.

The output will look like this:

The index is 0 The index is 1 The index is 2 The index is 3 The index is 4 The index is 5 The index is 6 The index is 7 The index is 8 The index is 9

Applying the key and index Variables

Now, let’s see how using both the key and index variables will look like.

 // Declare an array $arr = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]; $index = 0; foreach ($arr as $key => $value) < echo "The index is $index"; $index = $key + 1; echo "\n"; > ?>

In the example above, the value of the key variable is kept with an increment within the index variable. So, in this case, both the key and index variables are used for finding the index of foreach.

Describing the foreach Loop in PHP

In PHP, the foreach loop is applied for looping through a block of code for every element inside the array. It is essential to note that the foreach loop only operates on objects and arrays. Once you try to use it on a variable with a different data type, it will issue an error.

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Find the Foreach Index in PHP

1. Use the key Variable to Find the Foreach Index in PHP
2. Use index Variable to Find the Foreach Index in PHP
3. Use Both key and index Variable to Find the Foreach Index in PHP

In this article, we will introduce methods to find the foreach index.

• Using the key variable
• Using the index variable
• Using both the key and index variable

Use the key Variable to Find the Foreach Index in PHP

The variable key stores the index of each value in foreach loop. The foreach loop in PHP is used as follows.

foreach($arrayName as $value)  //code  > 

The variable value stores the value of each element of the array.

php $array = array(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);  foreach ($array as $key => $value)   echo "The index is = " . $key . ", and value is = ". $value;  echo "\n"; > ?> 

The key variable here contains the index of foreach loop. The variable value shows the value of each element in the array.

The index is = 0, and the value is = 1 The index is = 1, and the value is = 2 The index is = 2, and the value is = 3 The index is = 3, and the value is = 4 The index is = 4, and the value is = 5 The index is = 5, and the value is = 6 The index is = 6, and the value is = 7 The index is = 7, and the value is = 8 The index is = 8, and the value is = 9 The index is = 9, and the value is = 10 

Use index Variable to Find the Foreach Index in PHP

The variable index is used as an additional variable to show the index of foreach in each iteration.

php // Declare an array  $arr = array(1, 2, 3, 4, 5, 6, 7, 8, 9, 10); $index = 0;  foreach($arr as $key=>$val)   echo "The index is $index";  $index++;  echo "\n"; > ?> 

The index variable is first initialized with a value. It is then incremented each time the loop iterates.

The index is 0 The index is 1 The index is 2 The index is 3 The index is 4 The index is 5 The index is 6 The index is 7 The index is 8 The index is 9 

Use Both key and index Variable to Find the Foreach Index in PHP

Now, we will use both the key variable and an additional variable index to find the index of foreach .

php  // Declare an array  $arr = array(1, 2, 3, 4, 5, 6, 7, 8, 9, 10); $index = 0;  foreach ($arr as $key=>$value)   echo "The index is $index";  $index = $key+1;  echo "\n"; >  ?> 

We have stored the value of the key variable with an increment in its value in the index variable. In this way, we can find the index of foreach using both the key variable and index variable.

The index is 0 The index is 1 The index is 2 The index is 3 The index is 4 The index is 5 The index is 6 The index is 7 The index is 8 The index is 9 

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