c语言结构体可以通过等号复制么？

#include <stdio.h>
#include <stdlib.h>

struct test
{
    int a[5];
};


void print_test(struct test* a, const char* msg)
{
    int i;
    printf("%s:\t", msg);
    for (i = 0; i < 5; ++i)
        printf("%d ", a->a[i]);
    printf("\n");
}


void reset(struct test* input, int start)
{
    int i;
    struct test tmp;
    for (i = 0; i < 5; ++i)
        tmp.a[i] = start + i;

    *input = tmp;
}

int main()
{
    struct test r1, r2, r3;
    int i;
    for (i = 0; i < 5; ++i) {
        r1.a[i] = i;
        r2.a[i] = i + 20;
        r3.a[i] = i + 40;
    }

    print_test(&r1, "r1");
    print_test(&r2, "r2");
    print_test(&r3, "r3");

    r1 = r2;
    r2 = r3;
    reset(&r3, 80);

    print_test(&r1, "r1");
    print_test(&r2, "r2");
    print_test(&r3, "r3");

    return(0);
}

我以前一直以为结构体复制需要用memcpy这种东西，今天才知道可以直接用=号，求教一下各位。