How to generate random numbers between 2 values, inclusive?

Question

I need help figuring out how to generate a set amount of random numbers between two user-inputted values, inclusively. Just so you know, I have searched for this but am not finding what I have just stated. Here is my code:

#include <iostream>
#include <ctime>
#include <cstdlib>

using namespace std;

int main()
{
    int userBeg, userEnd, outPut;

    cout << "Enter a start value: ";
    cin >> userBeg;
    cout << "Enter an end value: ";
    cin >> userEnd;

    srand(time(NULL)); //generates random seed val

    for (int i = 0; i < 5; i++) {
      //prints number between user input, inclusive
    outPut = rand()%((userEnd - userBeg) + 1); 
    cout << outPut << "  ";
    }//end for

    return 0;
}//end main 

I'm confused with the output I get for the following ranges: 1-100 yield output numbers which fall in-between, but not including, the boundaries such as 50, 97, 24, 59, 22. But, 10-20 yield numbers such as 1, 14, 6, 12, 13. Here, the output is outside of the boundaries as well as in-between them. What am I doing wrong?

Thank you in advance for your help!

Answer 1

rand returns number between 0 and RAND_MAX. By taking modulo userEnd - userBeg + 1 the boundaries will be limited to 0 and userEnd - userBeg. If the random number should be within given boundaries, then userBeg should be added, so the calculus becomes

    outPut = rand()%((userEnd - userBeg) + 1) + userBeg;