Зимске чаролије

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

#define MAX_SIZE (30 + 1)

typedef struct slatkis_st{
    char naziv[MAX_SIZE];
    double kolicina;
    unsigned int gramaza;
    char vrsta[MAX_SIZE];
    struct slatkis_st *sl;
}SLATKISH;

void list_init(SLATKISH**);
void delete_list(SLATKISH**);
SLATKISH* make_slatkish(char*,double,unsigned int,char*);
void add_to_list(SLATKISH**,SLATKISH*);

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

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

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

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

SLATKISH* make_slatkish(char* naziv,double kolicina,unsigned int gramaza,char* vrsta){
    SLATKISH *new = (SLATKISH*)malloc(sizeof(SLATKISH));
    if(new == NULL){
        printf("Nije moguce zauzeti memoriju.");
        exit(EXIT_FAILURE);
    }
    strcpy(new->naziv,naziv);
    strcpy(new->vrsta,vrsta);
    new->kolicina = kolicina;
    new->gramaza = gramaza;
    new->sl = NULL;
    return new;
}

void add_to_list(SLATKISH** glava,SLATKISH* new){
    if(*glava == NULL){
        *glava = new;
    }else{
        SLATKISH* 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.",name);
        exit(EXIT_FAILURE);
    }
    return f;
}

void load(FILE* f,SLATKISH** glava){
    char naziv[MAX_SIZE],
         vrsta[MAX_SIZE];
    double kolicina;
    unsigned int gramaza;
    while(fscanf(f,"%s %lf %u %s",
                                  naziv,
                                  &kolicina,
                                  &gramaza,
                                  vrsta) != EOF){
        add_to_list(glava,make_slatkish(naziv,kolicina,gramaza,vrsta));
    }
    return;
}

void save(FILE* f,SLATKISH* glava,char* param){
    SLATKISH*   t = glava,
            *   max = NULL;
    while(t != NULL){
        if(strcmp(t->vrsta,param) == 0){
            double tmp = t->kolicina*(t->gramaza/100.);
            fprintf(f,"%s %u %.2lf\n",t->naziv,t->gramaza,t->kolicina);
            if(max == NULL){
                max = t;
            }else{
                if( (max->kolicina*(max->gramaza/100.)) < tmp){
                    max = t;
                }
            }
        }
        t = t->sl;
    }
    if(max == NULL){
        fprintf(f,"\nNe postoji max el.");
    }else{
        fprintf(f,"\nSlatkis sa najvise secera je: %s\nKolicina secera je: %.2lf",max->naziv,max->kolicina*(max->gramaza/100.));
    }
    return;
}