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 shows another way in which <random> is easier to use than rand() and manually computing your own distributions.

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 number using rand() which is in the specific range from min to …

Jul 24, 2013 · You need to seed the random number generator, from man 3 rand. If no seed value is provided, the rand() function is automatically seeded with a value of 1. and. The srand() function sets its argument as the seed for a new sequence of …

Apr 24, 2010 · int GetRandomNumber(int min, int max) { Random rand = new Random((int)DateTime.Now.Ticks); return rand.Next(min, max); } if you are looking for random number generator for normal distribution, you might use a Box-Muller transformation. Check the answer by yoyoyoyosef in Random Gaussian Variable Question.

May 5, 2011 · The 50 in rand.nextInt(50) will only give the maximum in this situation. rand.nextInt(50) will return an integer between 0 (inclusively) and 50 (exclusively) (in other words [0-49]). We add 1 to have [1-50]. So, if you take 45 as a minimum and add it to rand.nextInt(50), you'll have a value between 45 and 94 inclusively. –

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 (%) operator gives the remainder after dividing. When you use it with rand() you are using it to set an upper limit (n) on what the random number can be.

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 between calls. If rand_r() is called with the same initial value for the integer pointed to by seedp, and that value is not modified between calls, then the same pseudo-random sequence ...

Now, assuming you obtained integers in the range from 0 to RAND_MAX - 1 (inclusively) by using std::rand() % RAND_MAX, the chance of getting a 0 would now be doubled, since it will be the result when std::rand() returns either 0 or RAND_MAX. Any other number will only be obtained when directly returned by std::rand().

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 get what you want you will need to move the +1 outside the computation: r = ((double) rand() / (RAND_MAX)) + 1;

rand gives you a pseudo random sequence of numbers. This number is generated by an algorithm that returns a sequence of apparently non-related numbers each time it is called. This algorithm uses a seed to generate the series, which should be initialized to some distinctive value using function srand.