Question

How to generate random integer in a range (min...max) in C++

Answer 1

#include <iostream>
#include <cstdlib>  
#include <ctime>
 
int main()
{
    srand(time(NULL));
  
    int min = 3, max = 14;
  
    for (int i = 0; i < 20; i++) {
        int n = min + (rand() % (int)(max - min + 1));
        std::cout << n << "\n";
    }
}
  
  
/*
run:
  
10
8
3
12
11
9
11
14
7
10
6
6
11
7
9
13
8
5
12
7
  
*/

 

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Answer 2

#include <iostream>
#include <random>  
 
// C++ 11
 
int main()
{
    int min = 3, max = 14;
     
    std::random_device rd;    
    std::mt19937 random_generator(rd());
    std::uniform_int_distribution<int> uni(min, max); 
 
    for (int i = 0; i < 20; i++) {
        auto n = uni(random_generator);
        std::cout << n << "\n";
    }
}
 
 
/*
run:
 
12
8
3
9
12
11
7
7
3
5
6
3
8
4
5
14
8
7
12
6
 
*/

 

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Answer 3

#include <iostream>
#include <random>  
  
// C++ 11
  
int main()
{
    std::random_device rd;
    int min = 3, max = 14;
  
    std::default_random_engine dre(rd());
    std::uniform_int_distribution<int> uniform_int_dist(min, max);
      
    for (int i = 0; i < 20; i++) {
        int randomNum = uniform_int_dist(dre);
        std::cout << randomNum << "\n";
    }
}
 
 
 
/*
run:
 
12
7
13
14
10
12
6
10
6
11
4
3
13
4
6
8
8
14
6
4
 
*/

 

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Answer 4

#include <iostream>
#include <cstdlib> // For rand() and srand()
#include <ctime>   // For time()

int main() {
    srand(static_cast<unsigned int>(time(0)));

    int min = 3, max = 14;

    for (int i = 0; i < 20; i++) {
        int randomNum = rand() % (max - min + 1) + min;
        std::cout << randomNum << "\n";
    }
}
 
 
 
/*
run:
 
12
11
6
4
6
6
14
9
9
6
4
11
3
4
13
8
11
13
4
9
 
*/

 

70+ SQL courses for beginners and professionals