Oct 28, 2015 · Like rand(), rand_r() returns a pseudo-random integer in the range [0, RAND_MAX]. The seedp argument is a pointer to an unsigned int that is used to store state …

Oct 24, 2013 · The equivalent half-open range is [0, n), and rand() % n == rand() % (n-0) + 0. So the lesson is: don't confuse half-open ranges for closed ranges. A second lesson is that this …

Sep 27, 2011 · The c++ rand() function gives you a number from 0 to RAND_MAX (a constant defined in <cstdlib>), which is at least 32767. (from the c++ documentation) The modulus (%) …

Jul 30, 2009 · Related: How to generate a random int in C?. Here is my answer there, which contains the definition for my int utils_rand(int min, int max) func, which returns a random …

Mar 14, 2013 · From the rand man page: The function rand() is not reentrant or thread-safe, since it uses hidden state that is modified on each call. So don't use it with threaded code. Use …

If we use more than 53 bits, we get rounding bias. Some programmers write code like rand() / (double)RAND_MAX, but rand() might return only 31 bits, or only 15 bits in Windows. …

Nov 17, 2013 · Using the remainder to clamp outputs from rand to a specified range will usually cause bias in the results. To be specific, if the range of the generator (RAND_MAX in the case …

rand and srand are usually implemented as a simple LCG, you can easily write your own (it's few lines of code) without looking for the sources of rand and srand. Notice that, if you need …

Oct 18, 2018 · None of the answers here explains the real reason of being rand() bad. rand() is a pseudo-random number generator (PRNG), but this doesn't mean it must be bad. Actually, …

No, because RAND_MAX is typically expanded to MAX_INT. So adding one (apparently) puts it at MIN_INT (although it should be undefined behavior as I'm told), hence the reversal of sign. To …