Php read array while

Как вывести PHP массив

Примеры использования PHP функций и циклов для вывода всех элементов массива в окно браузера.

Функция print_r()

Функция print_r() выводит информацию о переменной в удобочитаемом виде. Чтобы отобразить пробелы и переносы результат функции нужно обернуть в тег .

$array = array( 'Andi', 'Benny', 'Cara', 'Danny', 'Emily', ); echo '
'; print_r($array); echo '
 
'; 
 
Результат:
 
Array ( [0] => Andi [1] => Benny [2] => Cara [3] => Danny [4] => Emily )
 
 Функция var_dump() 
 
Функция var_dump() отображает информацию о переменной, включая тип и значение.
 
$array = array( 'Andi', 'Benny', 'Cara', 'Danny', 'Emily', ); echo '
'; var_dump($array); echo '
 
'; 
 
Результат:
 
array(5) < [0]=>string(4) "Andi" [1]=> string(5) "Benny" [2]=> string(4) "Cara" [3]=> string(5) "Danny" [4]=> string(5) "Emily" >
 
 var_export() 
 
Функция var_export() возвращает строковое представление переменной в виде полноценного PHP-кода.
 
$array = array( 'Andi', 'Benny', 'Cara', 'Danny', 'Emily', ); echo '
'; echo var_export($array); echo '
 
';
 
Результат:
 
array ( 0 => 'Andi', 1 => 'Benny', 2 => 'Cara', 3 => 'Danny', 4 => 'Emily', )
 
 Цикл foreach 
 
Цикл foreach специально создан для поэлементного перебора массивов.
 
$array = array( 'Andi', 'Benny', 'Cara', 'Danny', 'Emily', ); foreach ($array as $row) < echo $row . "
\r\n"; >
 
Результат:
 
Andi 
Benny 
Cara 
Danny 
Emily
 
Пример с выводом нумерованного списка с использованием индексов массива:
 
$array = array( 'Andi', 'Benny', 'Cara', 'Danny', 'Emily', ); foreach ($array as $n => $row) < echo ($n + 1) . '.' . $row . "
\r\n"; >
 
Результат:
 
1.Andi 
2.Benny 
3.Cara 
4.Danny 
5.Emily
 
Чтобы не выводить последний 
, добавим условие:
 
$array = array( 'Andi', 'Benny', 'Cara', 'Danny', 'Emily', ); foreach ($array as $n => $row) < echo ($n + 1) . '.' . $row; if ($n < count($array) - 1) < echo "
\r\n"; > >
 
Результат:
 
1.Andi 
2.Benny 
3.Cara 
4.Danny 
5.Emily
 
 Цикл for 
 
Цикл for подойдет только в случаях, когда индексы массива имеют непрерывную нумерацию.
 
$array = array( 'Andi', 'Benny', 'Cara', 'Danny', 'Emily', ); for ($n = 0; $n < count($array); $n++) < echo $n + 1 . '.' . $array[$n] . "
\r\n"; >
 
Результат:
 
1.Andi 
2.Benny 
3.Cara 
4.Danny 
5.Emily
 
 Цикл while 
 
Цикл while такое же работает как и for .
 
$array = array( 'Andi', 'Benny', 'Cara', 'Danny', 'Emily', ); $index = 0; while ($index < count($array)) < echo $index + 1 . '.' . $array[$index] . "
\r\n"; $index++; >
 
Результат:
 
1.Andi 
2.Benny 
3.Cara 
4.Danny 
5.Emily
 
 Функция implode() 
 
Также, для вывода массива удобно использовать функцию implode() , которая объединяет элементы массива через разделитель.
 
$array = array( 'Andi', 'Benny', 'Cara', 'Danny', 'Emily', ); echo implode("
\r\n", $array);
 
Результат:
 
Andi 
Benny 
Cara 
Danny 
Emily
 
Источник
 
6 ways to loop through an array in php
 
Today, we will learn how to loop through an array in PHP using while ****loop, for loop, & various PHP Array functions.
 
PHP is one of the easiest language and traversing through an array in php is very easy. Infact, most popular way to access items in array in php is using loops : while, for & do..while
 
1. While loop
 
The while loop is very common loop among all languages and PHP is not different. In fact, while loop is one of the most popular method to iterate over PHP array.
 
while(expression) // Code to be executed >
 
It means that, while the given expression (or condition) is true, execute the code inside the curly brackets, and check the expression again. Keep doing it, until expression becomes false.
 
How to Iterate over PHP array using while loop
 
The PHP arrays have elements which can be accessed via its index position, right?
 
So, we can use the while loop to change the index position incrementally or decrementally therefore accessing every element (or selective elements as per the condition).
 
Here, we will create an index position variable and start with 0th position which is first in an array.
 
The condition will be to continue fetching element from an array til our index values is less than the count of array (or length of the given array).
 
Since, while loop will not increment our index variable automatically, we need to increment it inside the loop. Therefore, with each iteration, variable will move to next index position.
 
 $users = ['john', 'dave', 'tim']; $i = 0; while($i  count($users))  echo $users[$i]."\n"; $i++; > ?>
 
2. do while Loop
 
Well, personally it’s my least favorite loop in every programming language, so I’d probably say less.
 
The do while is another type of loop in php (and mostly all programming languages . except some functional languages .. Yes, I am looking at you Smalltalk )
 
It is mostly similar to while loop, except the ordering is reverse.
 
 
In while loop, condition or expression is checked first & if true, then the code inside the loop gets executed
 
In do while loop, code inside the loop gets executed first & then the condition is checked. If condition is true, then it will execute the code again and so on.
 
 
do  // Code to be executed > while(expression);
 
It means that, while the given expression (or condition) is true, execute the code inside the curly brackets, and check the expression again. Keep doing it, until expression becomes false.
 
Note: Don’t miss the semicolon at the end. I always forget that.
 
Without further ado, let’s recrete previous example using do while loop
 
How to loop through php array using do while loop
 
We will iterate over an array of users using do while loop.
 
 $users = ['john', 'dave', 'tim']; $i = 0; do  echo $users[$i]."\n"; $i++; > while($i  count($users)); ?>
 
3. For Loop
 
Let’s talk about the MOST popular loop. The for loop.
 
The for loop is my most favorite general loop (next one I use often for this particular usecase) for any general iterative usecase. It does the exactly same as while loop but it has different, more compact syntax.
 
for (expr1; expr2; expr3)  //Code to be executed > 
 
It looks very complex at first, but when you get bit experience, believe me, you will prefer this most of the time.
 
It has placeholder for three expressions (each are optional, so you can still use this loop just like while)
 
 
Expr1 — It gets executed once at the beginning of the loop, so normally it is used to initialize any counters to be used.
 
Expr2 — This is the condition part. At the beginning of each iteration, this expression gets evaluated and if true then only it will continue.
 
Expr3 — It gets execute at the end of the iteration. Normally used to increment/decrement our counters.
 
 
Let’s recreate our example using for loop.
 
How to loop through array using for loop in PHP
 
As shown below, it is exactly same as while loop, except it’s condensed and better syntax. Also, for one line statements, you can omit curly brackets 😉
 
 $users = ['john', 'dave', 'tim']; for($i = 0;$i  count($users);$i++) echo $users[$i]."\n"; ?> 
 
4. Foreach Loop
 
Talking about condensed syntax, let’s talk about another great and special loop — Foreach loop.
 
This loop is only helpful when you want to iterate over each item. If for example — you want to access only even position items, then sadly this loop is not for you, you need to use above loops.
 
But, for the particular use of accessing each item (see the pun?), foreach is my favorite and infact would be everyone’s favorite. It is very simply and easy to use.
 
//without key foreach (iterable_expression as $value) statement //with key foreach (iterable_expression as $key => $value) statement
 
Let’s checkout the example:
 
How to loop over array using foreach loop in PHP
 
Let’s recreate our example. We won’t need the keys (position) therefore we will use foreach without keys.
 
 $users = ['john', 'dave', 'tim']; foreach($users as $user) echo $user."\n"; ?>
 
5. array_walk
 
The array_walk is an array function provided by PHP which applies the given function to each element in the array, hence the name «array_walk».
 
array_walk(array|object &$array, callable $callback, mixed $arg = null): bool
 
 
array — It is the input array to iterate over.
 
callback — It is a function passed to this function which will act on each item one by one. This function takes two parameters — 1. Item value 2. Index position of the item
 
args — It is the optional arguments which if supplied, will be passed as third parameter to callback function.
 
 
It returns true when executed successfully.
 
Let’s recreate our example:
 
 $users = ['john', 'dave', 'tim']; function print_item($item, $key)  echo $item."\n"; > array_walk($users, 'print_item'); ?>
 
6. Array Iterator
 
This is quite advanced and complex way to iterate over an array. Honestly, I don’t see the reason why you would need to use this over other methods, but for the purpose of fun & learning, let’s explore this.
 
Here, we will create ArrayIterator object using ArrayObject function and use it to iterate over an array. It is based on pointer mechanism just like C++.
 
 $users = ['john', 'dave', 'tim']; $array_object = new ArrayObject($users); $array_iterator = $array_object->getIterator(); while( $array_iterator->valid() )  echo $array_iterator->current() . "\n"; $array_iterator->next(); > ?>
 
Conclusion
 
We saw 6 ways to loop over an array in PHP so far. Personally, I like to use foreach because it is very simple but you can use any of the above method. Hope, this helped.
 
Источник
 
Использование циклов в PHP
 
PHP имеет четыре вида циклов и операторы управления ими, рассмотрим поподробнее.
 
 Foreach – перебор массива 
 
Предназначен для перебора элементов массива.
 
 
$array = array( 1 => 'Значение 1', 2 => 'Значение 2', 3 => 'Значение 3', 4 => 'Значение 4', ); // Вывод ключей foreach ($array as $key => $val) < echo $key . '
'; > // Вывод значений foreach ($array as $key => $val) < echo $val . '
'; > 
 
Результат:
 
1 2 3 4 Значение 1 Значение 2 Значение 3 Значение 4
 
Альтернативный синтаксис foreach
 
 For – цикл с счетчиком 
 
Цикл работает пока выполняется заданное условие. Обычно применяется в качестве счетчика.
 
 
// Счетчик от 0 до 5 for ($n = 0; $n // Счетчик от 5 до 0 for ($n = 5; $n >= 0; $n--)
 
Результат:
 
Альтернативный синтаксис
 
$array = array( 'Значение 1', 'Значение 2', 'Значение 3', 'Значение 4', ); for ($n = 0; $n < count($array); $n++) < echo $array[$n] . '
'; >
 
Результат:
 
Значение 1 Значение 2 Значение 3 Значение 4
 
Альтернативный синтаксис for
 
 While – цикл с предусловием 
 
Т.е. если перед началом итерации условие выполняется, то цикл продолжает свою работу.
 
 
Результат:
 
Альтернативный синтаксис while
 
 Do-while – цикл с постусловием 
 
В отличии от while этот цикл проверяет выполнения условия после каждой итерации. Do-while не имеет альтернативного синтаксиса.
 
 
Результат:
 
 Управление циклами 
 
Break
 
Вызов break или break 1 в цикле останавливает его.
 
Для вложенных циклов используется break 2 и т.д.
 
Continue
 
Используется для пропуска итерации.
 
Результат:
 
Для вложенных циклов по аналогии с break 2 , break 3 – continue 2 , continue 3 .
 
Источник
 
PHP Loops (while, do while, foreach & for) Tutorial
 
In this tutorial, we learn how to control the flow of our application even further. We learn how PHP can help us iterate through sections of code with while, do-while, for and foreach loop statements.
 
We also cover so called nested loops, which are loops inside other loops. And finally, we compare each loop and explain when to use which one.
 
By default, the flow of an application written in PHP is sequential. It starts at the top and flows sequentially to the bottom. Many times we will need to alter this flow and allow specific sections of code to be repeated multiple times.
 
For this purpose, PHP offers us various types of iteration, or looping, logic which are capable of repeating sections of code. Iteration helps us with repetitive tasks and when dealing with big data.
 
As an example, let’s consider a database for a mailing list which contains entries for a name and email address.
 
When we want to send an email to everyone on the list, we will need to iterate through all the users in the database one by one. We then fetch their email address and send them an email.
 
  The interpreter will start at the first user and send an email to that user. If there are more users in the database, it will process the next user in the database and send them an email too.
 
This process loops over and over for all the users in the database, or until we tell it to stop.
 
PHP offers us four types of loop statements:
 
A while loop will tell the interpreter to execute its code block repeatedly, as long as the while expression remains true. The expression will be evaluated each time at the beginning of the loop’s iteration.
 
The basic form of a while loop is as follows.
 
Источник
 
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