Several ways to traverse arrays in php (for foreach list each while)

Comments: Calculate the number of elements in the array $arr first, and then use it in the for statement. This is very efficient. If it is for($i=0;$i

2. foreach statement traverses the array There are two ways to use the foreach statement to loop through an array. The first method is the one we use most. The introduction is as follows: First way: foreach(array_expression as $value){ //Loop body } example:

In each loop, the value of the current element is assigned to the variable $value, and The pointer inside the array moves backward one step. Therefore, the next element of the array will be obtained in the next loop, and the loop will not stop until the end of the array, ending the traversal of the array.

The second way: foreach(array_expression as $key=>$value){ //Loop body }

Example:

3. Combined use of list(), each() and while loop to traverse the array The each() function takes an array as a parameter, returns the key/value pair of the current element in the array, and moves the array pointer backward to the position of the next element. The list() function is not a real function, but a language structure of PHP. list() assigns values ​​to a set of variables in one step.

Example:

Output results:

Summary: Among the three methods, the foreach statement loops through the array and is more efficient. Recommended Use.