NAME

       dynarr, dynarr_init, dynarr_resize, dynarr_free - simple dynamic arrays

SYNOPSIS

       #include <publib.h>

       void dynarr_init(struct dynarr *da, size_t elsize);
       int dynarr_resize(struct dynarr *da, size_t newsize);
       void dynarr_free(struct dynarr *da);

DESCRIPTION

       These functions make it easier to use dynamic arrays, i.e., arrays that are allocated with
       malloc(3) and resized with realloc(3).  Below is a typical code fragment for  implementing
       a dynamic array that is resized as more input is read.

            char *p, *line;
            size_t alloc, len;

            len = 0;
            alloc = 1024;
            if ((line = malloc(alloc)) == NULL) abort();

            while (fgets(line + len, alloc-len, stdin) != NULL) {
                 len = strlen(line);
                 alloc += 1024;
                 if ((p = realloc(alloc)) == NULL) abort();
                 alloc = p;
            }

       (The  error  handling  is intentionally simplified.)  Below is the above fragment with the
       dynarr(3).

            struct dynarr da;

            dynarr_init(&da);
            while (fgets((char *)da.data + da.used, da.alloc-da.len, stdin) != NULL) {
                 da.used = strlen(da.data);
                 if (dynarr_resize(&da, da.alloc + 1024) == -1) abort();
            }

       The code is a bit simpler, and all the memory allocation details and  most  of  the  error
       checking code is hidden away.

       The dynamic array is represented by a struct dynarr:

            struct dynarr {
                void *data;
                size_t alloc, used;
            };

       The interface to the dynamic allocation has intentionally been made unopaque.

       dynarr_init  initializes a struct dynarr to be an empty array, dynarr_resize sets its size
       to be newsize, and dynarr_free frees the array (it will become an empty array again).

RETURNS

       dynarr_resize returns -1 if it failed, 0 if it succeeded.  It does not change the array in
       any way if it failed.

SEE ALSO

       publib(3), malloc(3), realloc(3), strdup(3)

AUTHOR

       Lars Wirzenius (lars.wirzenius@helsinki.fi)