usaa20/cv2/program.c

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

#define LINESIZE 100

struct pizza{
    char name[LINESIZE];
    float prize;
};

//read the name and prize
//push them to stack

int read_pizza(struct pizza* item){
   
    char line1[LINESIZE];
    char line2[LINESIZE];
 
    memset(line1, 0, LINESIZE);
    memset(line2, 0, LINESIZE);
    char *l1 = fgets(line1,LINESIZE,stdin);
    char *l2 = fgets(line2,LINESIZE,stdin);

    float value = strtof(line2, &l2);
    if(value == 0.0F){
       return 0;
    }
    if(l1 != NULL && line1[1] != 0){
        item->prize = value;
        strcpy(item->name, line1);
        return 1;   
    }   
}

//compare 2 elements

int compare(const void *a, const void *b){
    //to the value const void a(b) we will assign the value of the pointer to the structure
    struct pizza* pizza_a = (void*) a;
    struct pizza* pizza_b = (void*) b;
    float r = (pizza_a->prize > pizza_b->prize) - (pizza_a->prize < pizza_b->prize);
    if (r == 0){  //if prizes are identical, than check if names are in alphabetical order
        r = strcmp(pizza_a->name, pizza_b->name);
    }
    return r;
}

int main(){
    
    struct pizza jedalny_listok[100];
    memset(jedalny_listok, 0 , sizeof(struct pizza)*100);
    
    struct pizza item;
    int counter = 0;   
    
    //write menu to array
    while(stdin, read_pizza(&item)){
        strcpy(jedalny_listok[counter].name, item.name);
        jedalny_listok[counter].prize = item.prize;
        counter++;
    }

    qsort(jedalny_listok, counter, sizeof(struct pizza), compare);
    
    int i = 0;
    for(i = 0; i < counter; i++){
        printf("%s", jedalny_listok[i].name);
        printf("%f", jedalny_listok[i].prize);
        printf("\n");
    }
    return 0;
}