C ++ STL std :: random_shuffle无法通过自定义随机数生成器

Question

I want to random_shuffle a vector (I know that random_shuffle is depreciated), but I get a compile error when I pass my custom random function which I copied from another thread on here. Can someone show me how to call random_shuffle using the random number generator posted below?

random_shuffle(defects.begin(), defects.end(), xorshf96);

static unsigned int x=123456789, y=362436069, z=521288629;

unsigned int xorshf96(void) {          //period 2^96-1
    unsigned int t;
    x ^= x << 16;
    x ^= x >> 5;
    x ^= x << 1;

    t = x;
    x = y;
    y = z;
    z = t ^ x ^ y;

    return z;
}

Answer 1

xorshf96 does not meet the requirements of the RandomFunc argument to std::random_shuffle :

r - function object returning a randomly chosen value of type convertible to std::iterator_traits<RandomIt>::difference_type in the interval [0,n) if invoked as r(n)

It must take an argument and return a random number less than it. The function is in implementation of the Knuth Shuffle and that is how that algorithm works.

As a sample fix, you could provide:

unsigned int xorshf96_fixed(int n)
{
    return xorshf96() % n;
}

random_shuffle(defects.begin(), defects.end(), xorshf96_fixed);