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Simple vector-implementation in C
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "vector.h"
void vector_init(vector *v)
v->data = NULL;
v->size = 0;
v->count = 0;
int vector_count(vector *v)
return v->count;
void vector_add(vector *v, void *e)
if (v->size == 0) {
v->size = 10;
v->data = malloc(sizeof(void*) * v->size);
memset(v->data, '\0', sizeof(void*) * v->size);
if (v->size == v->count) {
v->size *= 2;
v->data = realloc(v->data, sizeof(void*) * v->size);
v->data[v->count] = e;
void vector_set(vector *v, int index, void *e)
if (index >= v->count) {
v->data[index] = e;
void *vector_get(vector *v, int index)
if (index >= v->count) {
return NULL;
return v->data[index];
void vector_delete(vector *v, int index)
if (index >= v->count) {
for (int i = index, j = index; i < v->count; i++) {
v->data[j] = v->data[i];
void vector_free(vector *v)
int main(void)
vector v;
vector_add(&v, "emil");
vector_add(&v, "hannes");
vector_add(&v, "lydia");
vector_add(&v, "olle");
vector_add(&v, "erik");
int i;
printf("first round:\n");
for (i = 0; i < vector_count(&v); i++) {
printf("%s\n", (char*)vector_get(&v, i));
vector_delete(&v, 1);
vector_delete(&v, 3);
printf("second round:\n");
for (i = 0; i < vector_count(&v); i++) {
printf("%s\n", (char*)vector_get(&v, i));
return 0;
#ifndef VECTOR_H__
#define VECTOR_H__
typedef struct vector_ {
void** data;
int size;
int count;
} vector;
void vector_init(vector*);
int vector_count(vector*);
void vector_add(vector*, void*);
void vector_set(vector*, int, void*);
void *vector_get(vector*, int);
void vector_delete(vector*, int);
void vector_free(vector*);

Do you have a license in mind for this gist? Can we assume it's an MIT license?


There is a bug in vector_delete. The v->size should be updated after new array is allocated (because it has different size than the old one). This leads to memory leaks and/or segfaults.


for vector_add, is it should be "memset(v->data, '\0', sizeof(void *) * v->size)", not sizeof(void)


vector_delete doesn't have to reallocate a new memory block. Especially if you aren't changing the size of the array and are only allowing one item to be deleted at a time, then just start at the index that you are going to delete and shift everything down one, setting the last index to NULL.


Just now noticed that people are using this. Sorry about the bugs -- I originally wrote this a long time ago, and wasn't a very accomplished C programmer at that point. I've revisited the code and fixed the bugs. Feel free to use the code under MIT license, if you wish.


i think line 60 "for (int i = index, j = index; i < v->count; i++) {" should be "for (int i = index+1, j = index; i < v->count; i++) {".

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