Random Number Generation in C++
Code:
//
// main.cpp
// VaultBox
//
// Created by Devharsh Trivedi on 3/11/21.
//
#include <iostream>
#include <iomanip>
#include <string>
#include <map>
#include <random>
#include <cmath>
#include <vector>
int main(int argc, const char * argv[]) {
std::random_device ranDev;
unsigned int num_ranDev = ranDev();
std::cout << num_ranDev << std::endl;
std::mt19937 mtGen(num_ranDev);
std::vector<unsigned long> indexes(10);
iota(indexes.begin(), indexes.end(), 0);
for(int i=0; i<10; i++) {
std::cout << indexes[i] << "\t";
}
std::cout << std::endl;
shuffle(indexes.begin(), indexes.end(), std::default_random_engine(num_ranDev));
for(int i=0; i<10; i++) {
std::cout << indexes[i] << "\t";
}
std::cout << std::endl;
iota(indexes.begin(), indexes.end(), 0);
for(int i=0; i<10; i++) {
std::cout << indexes[i] << "\t";
}
std::cout << std::endl;
shuffle(indexes.begin(), indexes.end(), std::default_random_engine(num_ranDev));
for(int i=0; i<10; i++) {
std::cout << indexes[i] << "\t";
}
std::cout << std::endl;
iota(indexes.begin(), indexes.end(), 0);
for(int i=0; i<10; i++) {
std::cout << indexes[i] << "\t";
}
std::cout << std::endl;
shuffle(indexes.begin(), indexes.end(), mtGen);
for(int i=0; i<10; i++) {
std::cout << indexes[i] << "\t";
}
std::cout << std::endl;
iota(indexes.begin(), indexes.end(), 0);
for(int i=0; i<10; i++) {
std::cout << indexes[i] << "\t";
}
std::cout << std::endl;
shuffle(indexes.begin(), indexes.end(), mtGen);
for(int i=0; i<10; i++) {
std::cout << indexes[i] << "\t";
}
std::cout << std::endl;
return 0;
}
4061520885
0 1 2 3 4 5 6 7 8 9
8 6 4 0 5 2 3 7 9 1
0 1 2 3 4 5 6 7 8 9
8 6 4 0 5 2 3 7 9 1
0 1 2 3 4 5 6 7 8 9
2 4 0 5 3 1 9 7 6 8
0 1 2 3 4 5 6 7 8 9
6 7 0 5 1 2 4 9 3 8
Program ended with exit code: 0
This example generates random numbers in modern C++ using the
This approach gives better quality and more control than rand, letting you choose the engine and the distribution. For security sensitive work, use a cryptographic generator rather than a general purpose one.
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