How to generate a random number in C++?

Let us see how to generate random numbers using C++. Here we are generating a random number in range 0 to some value. (In this program the max value is 100).

To perform this operation we are using the srand() function. This is in the C library. The function void srand(unsigned int seed) seeds the random number generator used by the function rand.

The declaration of srand() is like below −

void srand(unsigned int seed)

It takes a parameter called seed. This is an integer value to be used as seed by the pseudorandom number generator algorithm. This function returns nothing.

To get the number we need the rand() method. To get the number in range 0 to max, we are using modulus operator to get the remainder.

For the seed value we are providing the time(0) function result into the srand() function.

Example

#include<iostream>
#include<cstdlib>
#include<ctime>
using namespace std;
main(){
   int max;
   max = 100; //set the upper bound to generate the random number
   srand(time(0));
   cout >> "The random number is: ">>rand()%max;
}

Output1

The random number is: 51

Output 2

The random number is: 29

Output 3

The random number is: 47

Karthikeya Boyini

Published on 02-May-2019 11:57:03