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random_device::entropy

Estimates the randomness of the source.

double entropy() const;

The member function returns an estimate of the randomness of the source, as measured in bits. (In the extreme, a non-random source has an entropy of zero.)

 

// std_tr1__random__random_device_entropy.cpp 
// compile with: /EHsc 
#include <random> 
#include <iostream> 
 
typedef std::random_device Myceng; 
int main() 
    { 
    Myceng ceng; 
    Myceng::result_type compval = ceng(); 
 
    compval = compval;  // to quiet "unused" warnings 
 
    std::cout << "entropy == " << ceng.entropy() << std::endl; 
    std::cout << "min == " << ceng.min() << std::endl; 
    std::cout << "max == " << ceng.max() << std::endl; 
 
    std::cout << "a random value == " << ceng() << std::endl; 
    std::cout << "a random value == " << ceng() << std::endl; 
    std::cout << "a random value == " << ceng() << std::endl; 
 
    return (0); 
    } 
 
entropy == 0
min == 0
max == 4294967295
a random value == 2439379569
a random value == 2439379569
a random value == 2439379569

Header: <random>

Namespace: std

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