按指定值移动数组中的项目

Question

How would you go about circularly rotating the items in an array up or down by a specified value. For example

$value = 1; // circularly rotate by 1
$array = array(1,2,3,4,5);

// Should return

array(2,3,4,5,1);

The entire array is circularly rotated anti-clockwise by 1. 1 went to the end and 2 became the leading number in the array. I cannot find a reliable way to do this.

Answer 1

Use a for-loop with a specification on how many items you want moved, and array_shift() to shift the array. Then add the first element to a shifted array (which essentially moves the first item to the last element)

$shift = 2; // How many times you want to move it
$output = array(1, 2, 3, 4, 5);

for ($i = 0; $i < $shift; $i++) {
    array_push($output , array_shift($output));
}
print_r($output); // 3, 4, 5, 1, 2

Live demo

References

• http://php.net/manual/en/function.array-shift.php
• http://php.net/manual/en/function.array-push.php