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std::generate_canonical

From cppreference.com
< cpp‎ | numeric‎ | random
 
 
 
 
template< class RealType, size_t bits, class Generator >
RealType generate_canonical( Generator& g );
(since C++11)

Generates a random floating point number in range [0; 1).

To generate enough entropy, calls g() exactly k times, where k = max(1, ⌈ b / log
2
R ⌉)
and

Contents

[edit] Parameters

g - generator to use to acquire entropy

[edit] Return value

Floating point value in range [0; 1).

[edit] Exceptions

None except from those thrown by g

[edit] Notes

Some existing implementations have a bug where they may occasionally return 1.0 if RealType is float GCC #63176 LLVM #18767

[edit] Example

produce random numbers with 10 bits of randomness: this may produce only k*R distinct values

#include <random>
#include <iostream>
 
int main()
{
    std::random_device rd;
    std::mt19937 gen(rd());
    for(int n=0; n<10; ++n) {
        std::cout << std::generate_canonical<double, 10>(gen) << ' ';
    }
}

Output:

0.208143 0.824147 0.0278604 0.343183 0.0173263 0.864057 0.647037 0.539467 0.0583497 0.609219

[edit] See also

produces real values evenly distributed across a range
(class template) [edit]