Functions for allocating/freeing memory of data-arrays

char *char_alloc(size_t nr_of_char)
char *char_free(char *ptr, size_t nr_of_char)
int *int_alloc(size_t nr_of_int)
int *int_free(int *ptr, size_t nr_of_int)
double *double_alloc(size_t nr_of_double) 
double *double_free(double *ptr, size_t nr_of_double)

All this allocate functions will return a pointer to the allocated array which is big enough fo nr_of_...elements of the specific type. If the function fails it will return NULL. The free functions will free a memory block which is big enough for nr_of_...elements at the address ptr points to. The free functions will return the NULL pointer.