CODEWITHSUNDEEP
c++macosdynamic-library
jjpe
jjpe

Reputation: 684

dlsym() usage fails for rand

I'm trying to call rand using dlfcn.h (d.

I have this code, based on a project I'm working on. The core issue for me is that when used this way, it compiles and even runs, but its output is

cif: cif is OK
rand val: 16807

And the value of rand val is 16807 every time, contrary to what rand is supposed to do. What am I doing wrong here?

Upvotes: 0

Views: 66

Answers (1)

nneonneo
nneonneo

Reputation: 179462

You only call rand() once. If unseeded, rand() is probably going to use a static seed, probably zero (library-dependent).

Import srand too, and seed it with a reasonably random quantity - for example, you could do

timeval tv;
gettimeofday(&tv, NULL);
srand_ptr(tv.tv_sec ^ tv.tv_usec);

to seed it with the current time (seconds and microseconds).

Alternatively, on OS X, consider using arc4random instead, which is automatically seeded and generally produces better random numbers.

Upvotes: 1

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