C++ Exercises: Generate random integers in a specific range

Last update on April 12 2025 13:00:47 (UTC/GMT +8 hours)

8. Generate Random Integers in a Specific Range

Write a program in C++ to generate random integers in a specific range.

Visual Presentation:

Sample Solution:

C++ Code :

#include <cstdlib> // Including the C Standard Library for functions like srand and rand
#include <ctime> // Including the C Time Library for time related functions
#include <iostream> // Including the standard input/output stream library

using namespace std;

int main() 
{
    int ln, un; // Declare variables for lower and upper range of numbers

    cout << "\n\n Generate random integer in a specific range: \n"; // Display a message to prompt the user
    cout << " --------------------------------------------------\n";

    cout << " Input the lower range of number: "; // Prompt the user to input the lower range
    cin >> ln; // Read the input lower range from the user

    cout << " Input the upper range of number: "; // Prompt the user to input the upper range
    cin >> un; // Read the input upper range from the user

    srand(time(NULL)); // Seed the random number generator using the current time

    cout << " The random number between " << ln << " and " << un << " is: "; // Display the range of random numbers
    cout << ln + rand() % static_cast<int>(un - ln + 1) << endl; // Generate and display a random number in the specified range

    return 0; // Return 0 to indicate successful completion of the program
}

Sample Output:

Generate random integer in a specific range:                          
 --------------------------------------------------                    
 Input the lower range of number: 15                                   
 Input the upper range of number: 25                                   
 The random number between 15 and 25 is: 18 

Flowchart:

For more Practice: Solve these Related Problems:

• Write a C++ program to generate a random integer within a user-defined range using the modern C++ random library.
• Write a C++ program to produce a sequence of random numbers in a specific range and validate uniform distribution.
• Write a C++ program to generate random integers within a range, ensuring the results are reproducible via a seed value.
• Write a C++ program to simulate random number generation in a range and test edge cases with custom exception handling.

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