Here is the interface of my generic dynamic array;

/* dynamic array interface */#ifndef DA_HEADER#define DA_HEADER#include <stdlib.h> /* size_t *//* creates a new dynamic array, with each element of "size" bytes */void *danew(size_t unitsize);/* returns pointer to element after the last element */void *daend(void *arr);/* appends new element after last element    return pointer to array head*/void *daappend(void *arr, const void *elem);/*    removes the last element and returns a pointer to it or null if empty*/void *dapop(void *arr);/*  frees the array*/void dafree(void *arr);#endif /* DA_HEADER */

and this is the implementation of my generic dynamic array:

/* dynamic array implementation */#include <string.h> /* memcpy */#include <stdlib.h> /* free */#include "xalloc.h" /* xmalloc, xrealloc */struct dynamic_array {        size_t cap;        size_t len;        size_t unitsize;        char data[1];};#define DATAOFFSET ((unsigned long)(((struct dynamic_array*)0)->data))#define DA_STRUCT(DATAPTR) (struct dynamic_array *)((char *)DATAPTR-DATAOFFSET)void *danew(size_t unitsize){        /* -1 because we already have one byte in struct */        struct dynamic_array *da = xmalloc(sizeof(struct dynamic_array) +                                          unitsize - 1);        da->cap = 1;        da->len = 0;        da->unitsize = unitsize;        return &(da->data);}static __inline struct dynamic_array *__dagrow(struct dynamic_array *da,                                                            size_t size){        while(size > da->cap)                da->cap = 2*da->cap;        /* -1 because we already have one byte in sizeof(struct) */        return xrealloc(da, sizeof(struct dynamic_array) + da->unitsize*da->cap                                                         - 1);}void *daappend(void *arr, const void *elem){        struct dynamic_array *da = DA_STRUCT(arr);        da = __dagrow(da, da->len + 1);        memcpy(&da->data[da->unitsize * da->len++], elem, da->unitsize);        return &da->data;}void *dapop(void *arr){        struct dynamic_array *da = DA_STRUCT(arr);        if(!da->len)                return NULL;        return &da->data[da->unitsize * --da->len];}void *daend(void *arr){        struct dynamic_array *da = DA_STRUCT(arr);        return &da->data[da->unitsize * da->len];}void dafree(void *arr){        struct dynamic_array *da = DA_STRUCT(arr);        free(da);}

And this is the example usage:

#include <stdio.h>#include "dynamic_array.h"struct foo {        int number;        char *text;};int main(){        struct foo *myfoos = danew(sizeof(struct foo));        struct foo *tmp_ptr;        struct foo tmp;        int i;        int numbers[] = {1,2,3,4,5};        char *texts[] = {"ali", "veli","osman","zekiye","mahmut"};        for (i=0; i < 5; i++) {                tmp.number = numbers[i];                tmp.text   = texts[i];                myfoos = daappend(myfoos, &tmp);        }        /* Random access */        printf("3rd element is number: %d, text: %s", myfoos[2].number,                                                      myfoos[2].text);        printf("Accessing sequentially\n");        /* Sequential access */        for (tmp_ptr = myfoos; tmp_ptr != daend(myfoos); tmp_ptr++) {                printf("current element: number: %d, text: %s\n", tmp_ptr->number,                                                                tmp_ptr->text);        }        printf("Accessing LIFO\n");        /* LIFO access */        while((tmp_ptr = dapop(myfoos)))                printf("current element number: %d, text: %s\n", tmp_ptr->number,                                                               tmp_ptr->text);        return 0;}

• 1
  \$\begingroup\$I've removed thegenerics tag. C doesn't support generics in the way other languages do and the tag isn't appropriate here.\$\endgroup\$

  nhgrif

  – nhgrif

  2015-03-31 12:00:12 +00:00

  CommentedMar 31, 2015 at 12:00

2 Answers2

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