How To Generate Random Numbers In C++ With A Range

Random number generation is a common task in programming. C++ provides several in-built functions to handle random number generation.

However, generating random numbers within a specific range can be tricky. In this tutorial, we will discuss how to generate random numbers in C++ with a range.

Steps to generate random numbers in C++ with a range:

1. Include the necessary headers.

You will need to include two headers for this task: iostream and cstdlib.

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#include <iostream>
#include <cstdlib>

2. Seed the random number generator.

The rand() function in C++ generates random numbers based on a seed value. If you don’t seed the generator, you will get the same sequence of random numbers every time you run the program. To seed the generator, you can use the srand() function from cstdlib header. srand() takes an integer value as its argument. The most common way to seed the generator is to use the current time. This ensures that the seed value is different every time you run the program. You can get the current time using the time() function from ctime header.

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srand(time(NULL));

3. Generate random numbers within a range.

To generate random numbers within a range, you need to use the rand() function. But you also need to modify the output to ensure that the generated numbers fall within the desired range. You can do this by using the modulus operator (%). Here’s an example:

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int min_value = 5;
int max_value = 10;
int random_number = min_value + (rand() % (max_value - min_value + 1));

In this case, random_number will be a random integer between 5 and 10 (inclusive).

Full code:

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#include <iostream>
#include <cstdlib>
#include <ctime>
 
int main() {
    srand(time(NULL));
    int min_value = 5;
    int max_value = 10;
    int random_number = min_value + (rand() % (max_value - min_value + 1));
    std::cout << "Random number between " << min_value << " and " << max_value << ": " << random_number << std::endl;
    return 0;
}

Conclusion:

Generating random numbers within a range is easy in C++ if you know the proper way to use rand() and the modulus operator (%).

Seeding the generator with the current time ensures that you get a different sequence of random numbers every time you run the program.