PHP Traversal Array Common way (for,foreach,while, pointers, etc.)

1 iterating through an array with a For loop

Count ($arr) to count the number of array elements
The For loop can only be used for traversal, pure indexed arrays!! If an associative array exists, count counts the total number of two arrays
Traversing a mixed array with a For loop, resulting in an array out of bounds


$arr =array (1,2,3,4,5,6,7);
$num =count ($arr);//count better put it outside for the function to perform only once
for ($i =0; $i <count ($arr); $i + +) {
echo "{$i}==>{$arr [$i]}<br/>];
}

2.foreach Loop traversal Array (foreach can facilitate any type of array)

For example:

$arr =array (1,2,3,5,6,7, "one" =>9);
foreach ($arr as $item) {

echo "{$item}<br/>";
}
foreach ($arr as $key = = $item) {

echo "{$key}==>{$item}<br/>";
}

3.3. Use list (), each (), and while () to iterate through the array

Usage:

while (list ($key, $value) =each ($arr)) {

echo "{$key}-->{$value}<br/>";
}

List (): Used to assign each value of the array to each parameter of the list function. (The parameter of the list function must be less than or equal to the number of array elements)

Eg:list ($a, $b, $c) =[1,2,3];--> $a =1; $b =2; $c = 3;
Note: ①list parses an array when the index array is parsed directly
②list can selectively parse the value of an array by passing null arguments
List ($a, $b) =[1,2,3];--> $a =1; $b = 3;
Each (): Used to return the key-value pair in which the current pointer is in the array! And move the pointer back one bit;
Return value: Returns an array if the array has the next one. Contains an indexed array (0-key, 1-key) and an associative array ("Key"-Key, "value"-value);
If the pointer does not have the next one return false;

The pointer uses the next bit in the last digit after the ③ array is traversed using each (), and then each () always returns false
If you want to use Reset ($arr)

4. Traversing functions with array pointers
①next: Moves the array pointer back one bit. and returns the value of the next bit; no return false;
②prev: Moves the array pointer forward one bit. and returns the value of the next bit; no return false;
③end: Moves the array pointer to the last one. and returns the value of the next bit; the empty array returns false;
④reset: Returns the array pointer to the first bit. and returns the value of the first bit; the empty array returns false;
⑤key: Returns the key that the current pointer is in;
⑥current: Returns the value in which the current pointer is in place;

PHP Traversal Array Common way (for,foreach,while, pointers, etc.)