c_vector.c

#include <stdlib.h>
#include <assert.h>
#include <string.h>
#include "c_vector.h"

// Return the vector size
size_t vector_size(vector *v)
{
	return v->size;
}

// Grow the vector to at least this size
void vector_grow(vector *v, size_t new_size)
{
	while (v->capacity < new_size)
		v->capacity *= 2;

	v->data = realloc(v->data, sizeof(void*) *v->capacity);
	assert(v->data);
	// set all unused values to zero (potential performance hazard!)
	// memset(v->data+v->size, 0, sizeof(void) * (v->capacity - v->size));
}

// APPEND an element to a vector, may grow the vector
void vector_append(vector *v, void *e)
{
	// condition to increase v->data:
	// last slot exhausted
	if (v->size >= v->capacity)
		vector_grow(v, v->capacity * 2);
	
	v->data[v->size] = e;
	v->size++;
}

// SET an element at index to 'e'
void vector_set(vector *v, size_t index, void *e)
{
	if (index >= v->capacity) {
		vector_grow(v, index);
		return;
	}

	v->data[index] = e;
}

// GET an element at index
void *vector_get(vector *v, size_t index)
{
	if (index >= v->size) {
		return NULL;
	}

	return v->data[index];
}

// POPs an element at index; COSTLY OPERATION, AVOID IF POSSIBLE!
void *vector_pop(vector *v, size_t index)
{
	if (index >= v->size)
		return NULL;

	void *ret = v->data[index];

	size_t i, j;
	void **newarr = (void**)malloc(sizeof(void*) * v->capacity);
	
	for (i = 0, j = 0; i < v->size; i++) {
		if (i == index)
			continue;
		// at one moment, when i>index, 'i' will get in front of 'j'
		newarr[j] = v->data[i];
		j++;
	}
	
	free(v->data);
	v->data = newarr;
	v->size--;
	
	return ret;
}

// initialize the vector, give it some capacity an allocate space
void vector_init(vector *v)
{
	v->size = 0;
	v->capacity = 10;
	v->data = calloc(sizeof(void*), v->capacity);
}

// release the vector
void vector_free(vector *v)
{
	free(v->data);
}

c_vector.h

#ifndef __C_VECTOR_H__
#define __C_VECTOR_H__

typedef struct vector_ {
    void **data;
    size_t size;
    size_t capacity;
} vector;

// Return the vector size
size_t vector_size(vector *v);

// Grow the vector to at least this size
void vector_grow(vector *v, size_t new_size);

// APPEND an element to a vector, may grow the vector
void vector_append(vector *v, void *e);

// SET an element at index to 'e'
void vector_set(vector *v, size_t index, void *e);

// GET an element at index
void *vector_get(vector *v, size_t index);

// POPs an element at index; COSTLY OPERATION, AVOID IF POSSIBLE!
void *vector_pop(vector *v, size_t index);

// initialize the vector, give it some capacity an allocate space
void vector_init(vector *v);

// release the vector
void vector_free(vector *v);

#endif