Shulou(Shulou.com)06/02 Report--

This article mainly introduces "what are the ways of circular arrays in php". In daily operation, I believe that many people have doubts about the way of circular arrays in php. Xiaobian consulted all kinds of materials and sorted out simple and easy-to-use methods of operation. I hope it will be helpful for you to answer the questions of "what are the ways of circular arrays in php?" Next, please follow the editor to study!

Loop mode: 1, use the for statement to traverse the array; 2, use the foreach () statement to traverse the array; 3, use the whilestatement with list (), each () function to traverse the array; 4, use whilestatement with key (), current (), next () and other pointer functions to traverse the array.

Operating environment of this tutorial: windows7 system, PHP7.1 version, DELL G3 computer

Four ways of array loop traversal

1. Use for to loop through the array

Conut ($arr); used to count the number of array elements.

For loops can only be used for traversing, pure indexed arrays!

If there is an associative array, count counts the total number of the two arrays, and uses the for loop to traverse the mixed array, causing the array to cross the bounds!

Eg:

$arr = array; $num = count ($arr); / / count is best placed outside the for so that the function can execute the echo "number of elements of the array {$num}" only once; for ($arr as value) {echo "{$item}"

";} foreach ($arr as $key = > $value) {echo" {$key} = > {$item}

";}

For example, parse the following array:

$h61701 = array ("group1" = > array ("array" ("name" = > 14, "sex" = > "male"), array ("name" = > "Zhang San", "age" = > 14, "sex" = > "male"), array ("name" = > "Zhang San", "age" = > 14, "sex" = > "male"), "group2" = > array (array ("name" = > "Zhang San", "age" = > 14, "sex" = > "male")) Array ("name" = > "Zhang San", "age" = > 14, "sex" = > "male"), array ("name" = > "Zhang San", "age" = > 14, "sex" = > "male"), "group3" = > array ("name" = > "Zhang San", "age" = > 14, "sex" = > "male"), array ("name" = > "Zhang San", "age" = > 14, "sex" = > "male"), array ("name" = > "Zhang San", "age" = > 14) "sex" = > "male") Foreach ($h61701 as $key = > $value) {echo "{$key}

"; foreach ($value as $key1 = > $value1) {echo" No. "($key1+1)." A classmate

"; foreach ($value1 as $key2 = > $value2) {echo" {$key2} = > {$value2}

";} echo"

";} echo"

";}

3. Use list (), each (), while () to traverse the array

(key) list (): used to assign each value of the array to every parameter of the list function. (the argument to the list function must be less than or equal to the number of elements in the array)

Note:

① list () parses only indexed arrays when parsing arrays

② list can selectively parse the values of an array through null parameters.

(key) each (): returns the key-value pair where the current pointer of the array is located! And move the pointer back one bit.

Return value: returns an array if the pointer has the next bit. Contains an indexed array (0-key, 1-value) and an associative array ("key"-key, "value"-value); returns false if the pointer has no next bit

Eg:

While (list ($key,$value) = each ($arr)) {echo "{$key}-- > {$value}

";} reset ($arr)

! After the array is iterated through with each (), the pointer uses the next bit in the last bit; that is, it always returns false with each ()

If you still need to use it, use reset ($arr); function to reset the array pointer

Eg:

$arr = array (1 arr as 2 value 3, "one" = > 4 5 value 6); foreach ($arr as $value) {echo "{$item}

";} foreach ($arr as $key = > $value) {echo" {$key} = > {$item}

";} while (true) {$a = each ($arr); if ($a) {echo" {$a [0]}-> {$a [1]}

"; echo" {$a ['key']}-- > {$a [' value']}

";} else {break;}} while (list ($key,$value) = each ($arr)) {echo" {$key}-> {$value}

";} reset ($arr); while (list ($key,$value) = each ($arr)) {echo" {$key}-- > {$value}

";}

4. Use the array pointer to traverse the array

① next: moves the array pointer one bit back. And returns the value of the last bit; no false is returned

② prev: moves the array pointer forward one bit. And returns the value of the previous bit; no false is returned

③ end: moves the array pointer to the last bit and returns the value of the last bit; the empty array returns false

④ reset: restores the array pointer to the first position. And returns the value of the first bit; the empty array returns false

⑤ key: returns the key where the current pointer is located

⑥ current: returns the value where the current pointer is located

$arr = [1je 2je 3je 4, "one" = > 5]; while (true) {echo key ($arr); echo "-"; echo current ($arr); echo "

"; if (! next ($arr)) {break;}} reset ($arr); / / second way: do {echo key ($arr); echo"-"; echo current ($arr); echo"

";} while (next ($arr)); reset ($arr); at this point, the study of" what are the ways of looping arrays in php "is over, hoping to solve everyone's doubts. The combination of theory and practice can help you learn better, go and try it! if you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to strive to bring you more practical articles!

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.