Цене пице у свету

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define MAX_DRZAVA (3 + 1)
#define MAX_GRAD (2 + 1)
#define MAX_PIZZA (20 + 1)

typedef struct pizza_st{
    unsigned int cena;
    char drzava[MAX_DRZAVA];
    char grad[MAX_GRAD];
    char pizza[MAX_PIZZA];
    struct pizza_st *sl;
}PIZZA;

void list_init(PIZZA**);
void delete_list(PIZZA**);
PIZZA* make_pizza(unsigned int,char*,char*,char*);
void add_to_list(PIZZA**,PIZZA*);

FILE* safe_open(char*,char*);
void load(FILE*,PIZZA**);
void save(FILE*,PIZZA*,char*,char*);

int main(int argc,char** argv){
    if(argc != 5){
        printf("Nepravilan poziv programa.");
        return EXIT_FAILURE;
    }else{
        PIZZA* glava;
        FILE * file = safe_open(argv[3],"r");
        list_init(&glava);
        load(file,&glava);
        fclose(file);
        file = safe_open(argv[4],"w");
        save(file,glava,argv[1],argv[2]);
        fclose(file);
        delete_list(&glava);
        return EXIT_SUCCESS;
    }
}

void list_init(PIZZA** glava){
    *glava = NULL;
    return;
}

void delete_list(PIZZA** glava){
    PIZZA* t;
    while(*glava != NULL){
        t = *glava;
        *glava = (*glava)->sl;
        free(t);
    }
    return;
}

PIZZA* make_pizza(unsigned int cena,char* drzava,char* grad,char* pizza){
    PIZZA* new = (PIZZA*)malloc(sizeof(PIZZA));
    if(new == NULL){
        printf("Nije moguce zauzeti memorij.");
        exit(EXIT_FAILURE);
    }
    strcpy(new->drzava,drzava);
    strcpy(new->grad,grad);
    strcpy(new->pizza,pizza);
    new->cena = cena;
    new->sl = NULL;
    return new;
}

void add_to_list(PIZZA** glava,PIZZA* new){
    if(*glava == NULL){
        *glava = new;
    }else{
        PIZZA* t = *glava;
        while(t->sl != NULL){
            t = t->sl;
        }
        t->sl = new;
    }
    return;
}

FILE* safe_open(char* name,char* mode){
    FILE* f = fopen(name,mode);
    if(f == NULL){
        printf("Nije moguce otvoriti fajl %s.\n",name);
        exit(EXIT_FAILURE);
    }
    return f;
}

void load(FILE* f,PIZZA** glava){
    unsigned int cena;
    char drzava[MAX_DRZAVA],
         grad[MAX_GRAD],
         pizza[MAX_PIZZA];
    while(fscanf(f,"%u %s %s %s",
                                &cena,
                                drzava,
                                grad,
                                pizza) != EOF){
        add_to_list(glava,make_pizza(cena,drzava,grad,pizza));
    }
    return;
}

void save(FILE* f,PIZZA* glava,char* param_drzava,char* param_pizza){
    PIZZA*       t     = glava;
    unsigned int count = 0,
                 sum   = 0;
    while(t != NULL){
        fprintf(f,"%4u %s %s %s\n",
                                  t->cena,
                                  t->drzava,
                                  t->grad,
                                  t->pizza);
        if( (strcmp(t->drzava,param_drzava) == 0) && (strcmp(t->pizza,param_pizza) == 0) ){
            sum += t->cena;
            count++;
        }
        t = t->sl;
    }
    if(count != 0){
        fprintf(f,"\navg = %.2f",(float)sum/count);
    }else{
        fprintf(f,"\nNOT FOUND!");
    }
    return;
}