c# - Rotating array with one fixed value -

i'm building strong logic , randomized keygen @ base 'partial key verification'. need add random function rotanting array sample found here @ stack overflow have different needs mine.

i'm starting array:

   int[] q = new int[5];    (int = 0; < q.length; i++)    {        q[i] = i;    } 

now have:

q[0] = 0; q[1] = 1; q[2] = 2; q[3] = 3; q[4] = 4; 

i need clockwise need maintain value immutable, example q[2] = 2;

then first step should result (by adding + 1 clockwise):

q[0] = 1; q[1] = 3; //bypassed 2nd value q[2] = 2; q[3] = 4; q[4] = 0; //come 0 

a second step should (by adding again + 1 clockwise):

q[0] = 3; //bypassed 2nd value q[1] = 4;  q[2] = 2; q[3] = 0; //come 0 q[4] = 1; 

if possible need rollback function... lot

thanks both help: meanwhile created solution:

        (int = 0; < q.length; i++)         {             if (i == fixed_int) { } //donothing             else if ((q[i] + 1) == fixed_int) { q[i] = q[i] + 2; }             else if ((q[i] + 1) == (q.length + 1)) { q[i] = 0; }             else { q[i] = q[i] + 1; }         } 

this fail when fix value has not 2 more int forward it's not case. please don't use code, it's not working in situations. use accepted answer because rocks!

assuming array has @ least 2 elements, may try (set step +1 , -1 different rotations):

void rotate(int[] a, int fix, int step) {     int = (fix + step + a.length) % a.length;     int n = (fix - step + a.length) % a.length;     int t = a[i];     while(i != n)     {         int j = (i + step + a.length) % a.length;         a[i] = a[j];         = j;     }     a[n] = t; }