The Big Programming Thread - Page 264

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


typedef struct {
    short number;
    short priority;
} Item;

Item createItem (short number, short priority) {
    Item item;
    item.number = number;
    item.priority = priority;
    return item;
}

Item readItem () {
    short number;
    short priority;
    scanf("%hd %hd", &number, &priority);
    return createItem(number, priority);
}

void printItem (Item item) {
    printf("%hd %hd\n", item.number, item.priority);
}


typedef struct {
    int size;
    Item* items;
} Queue;

Queue* newQueue () {
    Queue* queue = malloc(sizeof(Queue));
    if( queue == NULL ){
        exit(EXIT_FAILURE);
    }
    queue->size = 0;
    queue->items = NULL;
    return queue;
}

void add (Queue* queue, Item item) {
    queue->size++;
    queue->items = realloc(queue->items, sizeof(Item) * queue->size);
    if( queue->items == NULL ){
        exit(EXIT_FAILURE);
    }
    queue->items[queue->size - 1] = item;
}

void printQueue (Queue* queue) {
    for( int i = 0; i < queue->size; i++ ){
        Item item = queue->items[i];
        printItem(item);
    }
}

void deleteQueue (Queue* queue) {
    free(queue->items);
    free(queue);
}


int main (int argc, char** argv){
    Queue* queue = newQueue();
    for( int i = 0; i < 5; i++ ){
        Item item = readItem();
        add(queue, item);
    }
    printQueue(queue);
    deleteQueue(queue);
}

/* I/O */
#include <stdio.h>

/* malloc, free, realloc, exit */
#include <stdlib.h>

/* increase size */
size++;

/* get more memory for more data */
*pQueue = realloc(*pQueue, (size * sizeof(queue)));

/* loop variable */
int i;

/* point to structure 'queue' */
queue *pQueue;

/* dynamic memory allocation */
pQueue = (queue *)malloc(size * sizeof(queue));

/* deallocate memory */
free(pQueue);

/* successful execution */
return 0;

/* global dynamic size of structure, it needs to be used for malloc and realloc */
static int size = 1;