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.

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. OpenSSL's RAND_bytes() seeds itself, perhaps by reading /dev/urandom in Linux.

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.

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 …

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;

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.

You get the same sequence because rand() is automatically seeded with the a value of 1 if you do not call srand(). Edit. Due to comments. rand() will return a number between 0 and RAND_MAX (defined in the standard library). Using the modulo operator (%) gives the remainder of the division rand() / 100. This will force the random number to be ...

int randint() { int random = rand(); return random; } int main() { // To get a unique sequence the random number generator should only be // seeded once during the life of the application. // As long as you don't try and start the application mulitple times a second // you can use time() to get a ever changing seed point that only repeats every ...

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.