C :: Convert From Array To List And Back

I need to convert from an array to a list and back.

array to list: (x,y) to int and int to (x,y)

I wrote this function:

Code:
/*
* inputs:
* coordX: column;
* coordY: line;
* nc: number of colums

[Code] ....

It works fine but the other way around is giving me sleeping problems. I was thinking something about this:

Code:
/*
* inputs: integer
* returns: X coordinate
*/
int inttoX(int n, int nc){
int coordX;

[Code] .....

I don't need the code, just want to continue... i'm a little blocked.