C++ generating random numbers

Question

My output is 20 random 1\'s, not between 10 and 1, can anyone explain why this is happening?

#include  
#include  
#include <         


        

Answer 1

(rand() % highest) + lowest + 1

Answer 2

You are generating a random number (ie (range*rand()/(RAND_MAX + 1.0))) whose value is between -1 and 1 (]-1,1[) and then casting it to an integer. The integer value of such number is always 0 so you end up with the lower + 0

EDIT: added the formula to make my answer clearer

Answer 3

random_integer = (rand() % 10) + 1 

That should give you a pseudo-random number between 1 & 10.

Answer 4

It's much easier to use the <random> library correctly than rand (assuming you're familiar enough with C++ that the syntax doesn't throw you).

#include <random>
#include <iostream>

int main() {
  std::random_device r;
  std::seed_seq seed{r(), r(), r(), r(), r(), r(), r(), r()};
  std::mt19937 eng(seed);

  std::uniform_int_distribution<> dist(1, 10);

  for(int i = 0; i < 20; ++i)
    std::cout << dist(eng) << " ";
}

Answer 5

Probably "10 * rand()" is smaller than "RAND_MAX + 1.0", so the value of your calculation is 0.