mem.c

#include <stdio.h>
#include <string.h>

typedef unsigned char rgba_t[4];

int main () {

	char a[8];
	memset(a, 70, 8);

	char b[4] = {65, 66, 67, 68};

	printf("a: %s\n", a);
	printf("b: %s\n", b);

	memcpy(a, b, 4);

	printf("a: %s\n", a);
	printf("b: %s\n", b);

	memcpy(a+3, b, 4);

	printf("a: %s\n", a);
	printf("b: %s\n", b);

	rgba_t pix = { 75, 75, 75, 75};

	memcpy(a, pix, 4);

	printf("a: %s\n", a);
	printf("pix: %s\n", pix);

	return 0;
}