An example of an C language method that implements circular shifting of arrays

algorithm

Reverse Array (array flip)

code

void reverse(int array[], int left, int right)
{
 int l, r;
 for (l = left, r = right; l < r; l++, r--)
 {
  array[l] = array[l] ^ array[r];
  array[r] = array[l] ^ array[r]; // l ^ r ^ r = l ^ 0 = l.
  array[l] = array[l] ^ array[r]; // l ^ r ^ l = r ^ 0 = r;
 }
}

The above code realizes the exchange of variable values efficiently through xor operation, please remember:

Any number that is different from zero is itself. Any number that is different from 1 is negative.

Cyclic shift to the left

Assuming that we cyclically shift the n bit to the left, the steps are:

Flip the first n bit elements of the array; Flip the rest of the array; The array is then flipped and the n bit is rotated to the left.

The order of the above steps can also be changed to step2 - > step1 - > step3.

code:

reverse(array, 0, left_shift_num - 1);
reverse(array, left_shift_num, array_size - 1);
reverse(array, 0, array_size - 1);

Cycle moves to the right

Assuming that we loop right shift the n bit, the steps are as follows:

Flip the post-ES39en bit element of the array; Flip the rest of the array; Flip the entire array, and you iterate over the n bit.

The order of the above steps can also be changed to step2 - > step1 - > step3.

code:

reverse(array, 0, array_size - right_shift_num - 1);
reverse(array, array_size - right_shift_num, array_size - 1);
reverse(array, 0, array_size -1);