Random number generation 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 pseudo-random 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 Code

using namespace std;
main() {
   int max;
   max = 100; //set the upper bound to generate the random number
   cout << "The random number is: "<<rand()%max;

Output 1

The random number is: 51

Output 2

The random number is: 29

Output 3

The random number is: 47

Updated on: 30-Jul-2019


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