Question

I need to generate a mask vector (unsigned char type) which contains 2 of ‘1’s only, i.e. 0x03, 0x50 and etc.

I also need these two ‘1’s distributed randomly in the vector.

How can I do this in c/c++?

Thank you!

Edit:
A more challenging and general case is asked here.
How to generate n random 1s in an unsigned char array in c/c++?

Answer 1

I would do like this:

srand(time(0));
int s[8];
for (int i=0; i<8; i++) s[i] = i;
// s[0], s[1] are two random locations for '1's
u = rand()%8;
swap(s[0], s[u]);
v = rand()%7+1;
swap(s[1], s[v]);
unsigned char c = (1 << s[0]) | (1 << s[1]);