typedef struct Watchtower {
    char *id;
    char *postcode;
    char *manager;
    int population;
    double x;
    double y;
} watchtower_t;

void checkInputArgs(int argc, char **argv, FILE **datasetFile, \
    FILE **polygonFile, FILE **outputFile);
watchtower_t** readWatchtowers(watchtower_t **watchtowers, FILE* datasetFile, \
    int *numWatchtowers);
void checkNullPointer(void *ptr);