Why do I receive the error \"Variable-sized object may not be initialized\" with the following code?
int boardAux[length][length] = {{0}};
You receive this error because in C language you are not allowed to use initializers with variable length arrays. The error message you are getting basically says it all.
6.7.8 Initialization
...
3 The type of the entity to be initialized shall be an array of unknown size or an object type that is not a variable length array type.