#include <stdio.h>
#define PART_MAX 20

void separate_product_code(const char *code, char warehouse[], char productid[], char qualifier[]);

int main(void) {
  char *code = "ATL1203S14",
       warehouse[PART_MAX], productid[PART_MAX], qualifier[PART_MAX];

  separate_product_code(code, warehouse, productid, qualifier);

  printf("Product code: %s\n", code);
  printf("Parts: %s, %s, %s\n", warehouse, productid, qualifier);
  return 0;
}

void separate_product_code(const char *code, char warehouse[], char productid[], char qualifier[]){
  sscanf(code, "%[abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ]" 
               "%[0123456789]" 
               "%s", 
               warehouse, productid, qualifier);
}