There are several operation functions for array pointers in php

There are 8 types of array pointer operation functions: 1. current(), returns the value pointed by the current array pointer; 2. next(), moves the pointer to the next bit and returns the value of that bit; 3. prev(), moves the pointer to the previous bit and returns the value of that bit; 4. reset(), resets the pointer to point to the first element; 5. end(), etc.

The operating environment of this tutorial: Windows 7 system, PHP version 8.1, DELL G3 computer

The array pointer functions include reset(), prev( ), current(), pos(), next(), end(), key(), each()

Among them reset(), prev(), current(), pos(), next( ) and end() are both functions related to the value of the array, while key() is only related to the key of the array. Each() can obtain the value and key of the array

current() function

The parameter is an array, passed by reference, and returns the value pointed to by the current array pointer. If the pointer moves beyond the end of the array, false is returned. If the array is empty, false is returned

The pointer of the array is at the first position of the array by default

<?php
$arr = [11,22,33,44,55,66];
echo current($arr);
?>

pos() function

An alias for current, the usage is the same.

next() function

The parameter is an array, passed by reference, moves the array pointer to the next bit, and returns the value of that bit. When there is no element in that bit Returns false, and an empty array will also return false

<?php
$arr = [11,22,33,44,55,66];
echo current($arr)."<br>";   //指针指向11
next($arr);                    //指针指向22
echo current($arr)."<br>";   //指针指向22
next($arr);                    //指针指向33
next($arr);                    //指针指向44
echo current($arr)."<br>";   //指针指向44
?>

prev() function

The parameter is an array, passed by reference , moves the array pointer to the previous bit, returns the value of that bit, returns false when there is no element in that bit, and an empty array will also return false

#

<?php
$arr = [11,22,33,44,55,66];
echo current($arr)."<br>";   //指针指向11
next($arr);                    //指针指向22
next($arr);                    //指针指向33
echo current($arr)."<br>";   //指针指向33
prev($arr);                    //指针指向22
echo current($arr)."<br>";   //指针指向22

?>

reset () Function

The parameter is an array, passed by reference, resets the internal pointer of an array to the first position, which is the position of the first element of the array, and then returns the first element The value, returns false if the array is empty

<?php
$arr = [11,22,33,44,55,66];
echo current($arr)."<br>";   //指针指向11
next($arr);                    //指针指向22
next($arr);                    //指针指向33
echo current($arr)."<br>";   //指针指向33
reset($arr);               //指针指向11
echo current($arr)."<br>";   //指针指向11
?>

end() function

The parameter is an array, reference Pass value, move the internal pointer of an array to the position of the last element of the array, and then return the value of the last element, return false if the array is empty

<?php
$arr = [11,22,33,44,55,66];
echo current($arr)."<br>";   //指针指向11
end($arr);                 //指针指向11
echo current($arr)."<br>";   //指针指向66
?>

key() function

The parameter is an array, passed by reference, and returns the key of the element pointed to by the current pointer. When there is no element in the bit pointed by the pointer, null is returned. , the empty array returns null

<?php
$arr = [11,22,33,44,55,66];
var_dump($arr);
echo current($arr)."<br>";   //当前指针指向11 
echo key($arr)."<br>";   //当前元素的键名
?>

each() function

The parameter is an array, passed by reference, and returns the current pointer Refers to the value and key of the element, and moves the pointer to the next bit

<?php
$arr = [11,22,33,44,55,66];
var_dump($arr);
echo current($arr)."<br>";   //指针指向11
next($arr);                    //指针指向22
echo current($arr)."<br>";   //指针指向22
$item = each($arr);          //指针指向33
print_r($item);                //指针指向33
echo current($arr)."<br>";   //指针指向33

?>

The use of this function is highly discouraged after php7.2

Warning

This function has been DEPRECATED as of PHP 7.2.0. Relying on this function is highly discouraged

Recommended learning: "PHP Video Tutorial》

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