dynamic buffer/array in C in 30 lines

buffer.h

#include <string.h>
#include <stdlib.h>

#define buffer(type) \
	typedef struct type##_buf { \
		size_t size; \
		type *buffer; \
	} type##_buf; \
	void _resize_buffer_##type(struct type##_buf *buf) { \
		type *newbuf = malloc((buf->size++)*sizeof(type)); \
		memcpy((void *)newbuf, (void *)buf->buffer, buf->size * sizeof(type)); \
		free(buf->buffer); \
		buf->buffer = newbuf; \
	} \
	void append_##type(struct type##_buf *buf, type element) { \
		buf->buffer[buf->size - 1] = element; \
		_resize_buffer_##type(buf); \
	} \
	type##_buf *new_##type##_buf() { \
		type##_buf *buffer = malloc(sizeof(type##_buf)); \
		buffer->size = 1; \
		buffer->buffer = malloc(sizeof(type)); \
		return buffer; \
	} \
	void remove_##type(struct type##_buf *buf, size_t index) { \
		type *newbuf = malloc((buf->size--)*sizeof(type)); \
		memcpy((void *)newbuf, (void *)buf->buffer, index*sizeof(type)); \
		memcpy((void *)(newbuf + index), (void *)(buf->buffer + index + 1), buf->size-index+sizeof(type)); \
		buf->buffer = newbuf; \
	}

buffertest.c

#include <stdio.h>

#include "buffer.h"

buffer(int);
buffer(char);

int
main(int argc, char **argv)
{
	int_buf *intbuf = new_int_buf();
	char_buf *charbuf = new_char_buf();

	append_int(intbuf, 10);
	append_int(intbuf, 20);
	append_int(intbuf, 30);
	append_int(intbuf, 40);
	append_int(intbuf, 50);
	append_int(intbuf, 60);

	append_char(charbuf, 'a');
	append_char(charbuf, 'b');
	append_char(charbuf, 'c');

	printf("char Size: %d\n", charbuf->size);
	printf("char Content: %c, %c, %c\n",
	       charbuf->buffer[0],
	       charbuf->buffer[1],
	       charbuf->buffer[2]);

	printf(" int Size: %d\n", intbuf->size);
	printf(" int Content: %d, %d, %d, %d, %d, %d\n",
	       intbuf->buffer[0],
	       intbuf->buffer[1],
	       intbuf->buffer[2],
	       intbuf->buffer[3],
	       intbuf->buffer[4],
	       intbuf->buffer[5]);

	remove_int(intbuf, 3);

	printf(" int Size: %d\n", intbuf->size);
	printf(" int Content: %d, %d, %d, %d, %d\n",
	       intbuf->buffer[0],
	       intbuf->buffer[1],
	       intbuf->buffer[2],
	       intbuf->buffer[3],
	       intbuf->buffer[4]);
}