Arrays

Interface for an abstract implementation of an array data structure.

Arrays of a particular Type are defined and initialized using the following code:

vrna_array(Type)  my_array;
vrna_array_init(my_array);

or equivalently:

vrna_array_make(Type, my_array);

Dynamic arrays can be used like regular pointers, i.e. elements are simply addressed using the [] operator, e.g.:

my_array[1] = 42;

Using the vrna_array_append macro, items can be safely appended and the array will grow accordingly if required:

vrna_array_append(my_array, item);

Finally, memory occupied by an array must be released using the vrna_array_free macro:

vrna_array_free(my_array);

Use the vrna_array_size macro to get the number of items stored in an array, e.g. for looping over its elements:

// define and initialize
vrna_array_make(int, my_array);

// append some items
vrna_array_append(my_array, 42);
vrna_array_append(my_array, 23);
vrna_array_append(my_array, 5);

// loop over items and print
for (size_t i = 0; i < vrna_array_size(my_array); i++)
  printf("%d\n", my_array[i]);

// release memory of the array
vrna_array_free(my_array);

Under the hood, arrays are preceded by a header that actually stores the number of items they contain and the capacity of elements they are able to store. The general ideas for this implementation are taken from Ginger Bill’s C Helper Library (public domain).

Defines

vrna_array(Type)

#include <ViennaRNA/datastructures/array.h>

Define an array.

vrna_array_make(Type, Name)

#include <ViennaRNA/datastructures/array.h>

Make an array Name of type Type.

VRNA_ARRAY_GROW_FORMULA(n)

#include <ViennaRNA/datastructures/array.h>

The default growth formula for array.

VRNA_ARRAY_HEADER(input)

#include <ViennaRNA/datastructures/array.h>

Retrieve a pointer to the header of an array input.

vrna_array_size(input)

#include <ViennaRNA/datastructures/array.h>

Get the number of elements of an array input.

vrna_array_capacity(input)

#include <ViennaRNA/datastructures/array.h>

Get the size of an array input, i.e. its actual capacity.

vrna_array_set_capacity(a, capacity)

#include <ViennaRNA/datastructures/array.h>

Explicitely set the capacity of an array a.

vrna_array_init_size(a, init_size)

#include <ViennaRNA/datastructures/array.h>

Initialize an array a with a particular pre-allocated size init_size.

vrna_array_init(a)

#include <ViennaRNA/datastructures/array.h>

Initialize an array a.

vrna_array_free(a)

#include <ViennaRNA/datastructures/array.h>

Release memory of an array a.

vrna_array_append(a, item)

#include <ViennaRNA/datastructures/array.h>

Safely append an item to an array a.

vrna_array_grow(a, min_capacity)

#include <ViennaRNA/datastructures/array.h>

Grow an array a to provide a minimum capacity min_capacity.

Typedefs

typedef struct vrna_array_header_s vrna_array_header_t

#include <ViennaRNA/datastructures/array.h>

The header of an array.

Functions

void *vrna__array_set_capacity(void *array, size_t capacity, size_t element_size)

#include <ViennaRNA/datastructures/array.h>

Explicitely set the capacity of an array.

Note

Do not use this function. Rather resort to the vrna_array_set_capacity macro

struct vrna_array_header_s

#include <ViennaRNA/datastructures/array.h>

The header of an array.

Public Members

size_t num

The number of elements in an array.

size_t size

The actual capacity of an array.