Undefined symbols for architecture x86_64 in xcode-Collection of common programming errors

I get a Undefined symbols for architecture x86_64 error when compile it.

I build a game tree and check which nodes of the tree is empty using isEmpty() function.

Although there shows no errors,im not sure about the way i pass the two-dimensional array tree into the isEmpty() function.

//#include "header.h"
#define YES 10
#define NO 20

struct Node
    Node ** children;
    int     childCount;
    char name[1];
    int empty;//YES or NO
    int sequence;
    double  value;

using namespace std;

bool isEmpty(Node, int);

bool isEmpty(Node **ptr, int bsize) {    
    for (int i = 0; iempty == YES){
                return true;
    return false;

int main (int argc, const char * argv[])
    int size  = 4;
    Node tree[size][size];
// some stuff
    if (isEmpty(tree[size][size], size)) {

Originally posted 2013-11-09 20:53:45.