C++ || How To Shuffle & Randomize An Array/Vector/Container Using C++

February 09, 2021 admin No comments

The following is a module with functions which demonstrates how to randomize and shuffle the contents of an array/vector/container using C++.

The following template function is a wrapper for the std::shuffle function.

1. Shuffle – Integer Array

The example below demonstrates the use of ‘Utils::shuffle‘ to randomize an integer array.





		
		
			1. Shuffle - Integer Array
			
C++
			
			// Shuffle - Integer Array

// Declare numbers
int numbers[] = { 1987, 19, 22, 2009, 2019, 1991, 28, 31 };

// Get array size
int size = sizeof(numbers) / sizeof(numbers[0]);

// Get results
Utils::shuffle(numbers, numbers + size);

// Display results
for (const auto& item : numbers) {
    std::cout << item << std::endl;
}

// example output:
/*
    28
    1991
    22
    1987
    19
    2019
    2009
    31
*/
			
				
					
				
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						// Shuffle - Integer Array
 
// Declare numbers
int numbers[] = { 1987, 19, 22, 2009, 2019, 1991, 28, 31 };
 
// Get array size
int size = sizeof(numbers) / sizeof(numbers[0]);
 
// Get results
Utils::shuffle(numbers, numbers + size);
 
// Display results
for (const auto& item : numbers) {
    std::cout << item << std::endl;
}
 
// example output:
/*
    28
    1991
    22
    1987
    19
    2019
    2009
    31
*/

2. Shuffle – String Vector

The example below demonstrates the use of ‘Utils::shuffle‘ to randomize a string vector.





		
		
			2. Shuffle - String Vector
			
C++
			
			// Shuffle - String Vector

// Declare names
std::vector<std::string> names = { "Kenneth", "Jennifer", "Lynn", "Sole" };

// Get results
Utils::shuffle(names.begin(), names.end());

// Display results
for (const auto& item : names) {
    std::cout << item << std::endl;
}

// example output:
/*
    Jennifer
    Sole
    Kenneth
    Lynn
*/
			
				
					
				
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						// Shuffle - String Vector
 
// Declare names
std::vector<std::string> names = { "Kenneth", "Jennifer", "Lynn", "Sole" };
 
// Get results
Utils::shuffle(names.begin(), names.end());
 
// Display results
for (const auto& item : names) {
    std::cout << item << std::endl;
}
 
// example output:
/*
    Jennifer
    Sole
    Kenneth
    Lynn
*/

3. Shuffle – Custom Object Vector

The example below demonstrates the use of ‘Utils::shuffle‘ to randomize a custom object vector.





		
		
			3. Shuffle - Custom Object Vector
			
C++
			
			// Shuffle - Custom Object Vector 

// Declare object
struct Person {
    int id;
    std::string name;
};

// Declare names 
std::vector<Person> people = {
    {31, "Kenneth"}, {28, "Jennifer"}, {87, "Lynn"},
    {91, "Sole"}, {22, "Kenneth"}, {19, "Jennifer"}
};

// Get results
Utils::shuffle(people.begin(), people.end());

// Display results
for (const auto& item : people) {
    std::cout << item.id << " - " << item.name << std::endl;
}

// example output:
/*
    28 - Jennifer
    19 - Jennifer
    22 - Kenneth
    87 - Lynn
    91 - Sole
    31 - Kenneth
*/
			
				
					
				
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						// Shuffle - Custom Object Vector 
 
// Declare object
struct Person {
    int id;
    std::string name;
};
 
// Declare names 
std::vector<Person> people = {
    {31, "Kenneth"}, {28, "Jennifer"}, {87, "Lynn"},
    {91, "Sole"}, {22, "Kenneth"}, {19, "Jennifer"}
};
 
// Get results
Utils::shuffle(people.begin(), people.end());
 
// Display results
for (const auto& item : people) {
    std::cout << item.id << " - " << item.name << std::endl;
}
 
// example output:
/*
    28 - Jennifer
    19 - Jennifer
    22 - Kenneth
    87 - Lynn
    91 - Sole
    31 - Kenneth
*/

4. Utils Namespace

The following is the Utils Namespace. Include this in your project to start using!





		
		
			Utils Namespace
			
C++
			
			// ============================================================================
//    Author: Kenneth Perkins
//    Date:   Feb 9, 2021
//    Taken From: http://programmingnotes.org/
//    File:  Utils.h
//    Description: Handles general utility functions
// ============================================================================
#pragma once
#include <random>
#include <chrono>
#include <algorithm>

namespace Utils {
    /**
    * FUNCTION: shuffle
    * USE: Shuffles a collection in the given range [first, last)
    * @param first: The first position of the sequence to be sorted
    * @param last: The last position of the sequence to be sorted
    * @return: N/A
    */
    template<typename RandomIt>
    void shuffle(RandomIt first, RandomIt last) {
        auto seed = static_cast<std::mt19937::result_type> (
            std::chrono::system_clock::now().time_since_epoch().count()
        );
        std::mt19937 generator(seed);
        std::shuffle(first, last, generator);
    }
}// http://programmingnotes.org/
			
				
					
				
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						// ============================================================================
//    Author: Kenneth Perkins
//    Date:   Feb 9, 2021
//    Taken From: http://programmingnotes.org/
//    File:  Utils.h
//    Description: Handles general utility functions
// ============================================================================
#pragma once
#include <random>
#include <chrono>
#include <algorithm>
 
namespace Utils {
    /**
    * FUNCTION: shuffle
    * USE: Shuffles a collection in the given range [first, last)
    * @param first: The first position of the sequence to be sorted
    * @param last: The last position of the sequence to be sorted
    * @return: N/A
    */
    template<typename RandomIt>
    void shuffle(RandomIt first, RandomIt last) {
        auto seed = static_cast<std::mt19937::result_type> (
            std::chrono::system_clock::now().time_since_epoch().count()
        );
        std::mt19937 generator(seed);
        std::shuffle(first, last, generator);
    }
}// http://programmingnotes.org/

5. More Examples

Below are more examples demonstrating the use of the ‘Utils‘ Namespace. Don’t forget to include the module when running the examples!





		
		
			More Examples
			
C++
			
			// ============================================================================
//    Author: Kenneth Perkins
//    Date:   Feb 9, 2021
//    Taken From: http://programmingnotes.org/
//    File:  program.cpp
//    Description: The following demonstrates the use of the Utils Namespace
// ============================================================================
#include <iostream>
#include <string>
#include <exception>
#include <vector>
#include "Utils.h"

void display(const std::string& message);

// Declare object
struct Person {
    int id;
    std::string name;
};

int main() {
    try {
        // Declare numbers
        int numbers[] = { 1987, 19, 22, 2009, 2019, 1991, 28, 31 };

        // Get array size
        int size = sizeof(numbers) / sizeof(numbers[0]);

        // Get results
        Utils::shuffle(numbers, numbers + size);

        // Display results
        for (const auto& item : numbers) {
            std::cout << item << std::endl;
        }

        display("");

        // Declare names
        std::vector<std::string> names = { "Kenneth", "Jennifer", "Lynn", "Sole" };

        // Get results
        Utils::shuffle(names.begin(), names.end());

        // Display results
        for (const auto& item : names) {
            std::cout << item << std::endl;
        }

        display("");

        // Declare names
        std::vector<Person> people = {
            {31, "Kenneth"}, {28, "Jennifer"}, {87, "Lynn"},
            {91, "Sole"}, {22, "Kenneth"}, {19, "Jennifer"}
        };

        // Get results
        Utils::shuffle(people.begin(), people.end());

        // Display results
        for (const auto& item : people) {
            std::cout << item.id << " - " << item.name << std::endl;
        }
    } catch (std::exception& e) {
        display("\nAn error occurred: " + std::string(e.what()));
    }

    std::cin.get();
    return 0;
}

void display(const std::string& message) {
    std::cout << message << std::endl;
}// http://programmingnotes.org/
			
				
					
				
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						// ============================================================================
//    Author: Kenneth Perkins
//    Date:   Feb 9, 2021
//    Taken From: http://programmingnotes.org/
//    File:  program.cpp
//    Description: The following demonstrates the use of the Utils Namespace
// ============================================================================
#include <iostream>
#include <string>
#include <exception>
#include <vector>
#include "Utils.h"
 
void display(const std::string& message);
 
// Declare object
struct Person {
    int id;
    std::string name;
};
 
int main() {
    try {
        // Declare numbers
        int numbers[] = { 1987, 19, 22, 2009, 2019, 1991, 28, 31 };
 
        // Get array size
        int size = sizeof(numbers) / sizeof(numbers[0]);
 
        // Get results
        Utils::shuffle(numbers, numbers + size);
 
        // Display results
        for (const auto& item : numbers) {
            std::cout << item << std::endl;
        }
 
        display("");
 
        // Declare names
        std::vector<std::string> names = { "Kenneth", "Jennifer", "Lynn", "Sole" };
 
        // Get results
        Utils::shuffle(names.begin(), names.end());
 
        // Display results
        for (const auto& item : names) {
            std::cout << item << std::endl;
        }
 
        display("");
 
        // Declare names
        std::vector<Person> people = {
            {31, "Kenneth"}, {28, "Jennifer"}, {87, "Lynn"},
            {91, "Sole"}, {22, "Kenneth"}, {19, "Jennifer"}
        };
 
        // Get results
        Utils::shuffle(people.begin(), people.end());
 
        // Display results
        for (const auto& item : people) {
            std::cout << item.id << " - " << item.name << std::endl;
        }
    } catch (std::exception& e) {
        display("\nAn error occurred: " + std::string(e.what()));
    }
 
    std::cin.get();
    return 0;
}
 
void display(const std::string& message) {
    std::cout << message << std::endl;
}// http://programmingnotes.org/

QUICK NOTES:
The highlighted lines are sections of interest to look out for.

The code is heavily commented, so no further insight is necessary. If you have any questions, feel free to leave a comment below.

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Posted in: Advanced, C++ Tags: c++, shuffle, vector

C++ || How To Shuffle & Randomize An Array/Vector/Container Using C++

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