std::uniform_real_distribution (3) - Linux Manuals

std::uniform_real_distribution: std::uniform_real_distribution


std::uniform_real_distribution - std::uniform_real_distribution


Defined in header <random>
template< class RealType = double > (since C++11)
class uniform_real_distribution;

Produces random floating-point values i, uniformly distributed on the interval [a, b), that is, distributed according to the probability density function:

      P(i|a,b) =

      b − a


std::uniform_real_distribution satisfies all requirements of RandomNumberDistribution

Template parameters

RealType - The result type generated by the generator. The effect is undefined if this is not one of float, double, or long double.

Member types

Member type Definition
result_type RealType
param_type the type of the parameter set, see RandomNumberDistribution.

Member functions

              constructs new distribution
constructor (public member function)
              resets the internal state of the distribution
reset (public member function)


              generates the next random number in the distribution
operator() (public member function)


              returns the distribution parameters
a (public member function)
              gets or sets the distribution parameter object
param (public member function)
              returns the minimum potentially generated value
min (public member function)
              returns the maximum potentially generated value
max (public member function)

Non-member functions

           compares two distribution objects
operator== (function)
           performs stream input and output on pseudo-random number distribution
operator<< (function template)


To create a distribution over the closed interval [a,b], std::nextafter(b, std::numeric_limits<RealType>::max()) may be used as the second parameter.
Some existing implementations have a bug where they may occasionally return b if RealType is float GCC_#63176 LLVM_#18767. This is caused by LWG_issue_2524


print 10 random numbers between 1 and 2
// Run this code

  #include <random>
  #include <iostream>

  int main()
      std::random_device rd; //Will be used to obtain a seed for the random number engine
      std::mt19937 gen(rd()); //Standard mersenne_twister_engine seeded with rd()
      std::uniform_real_distribution<> dis(1.0, 2.0);
      for (int n = 0; n < 10; ++n) {
          // Use dis to transform the random unsigned int generated by gen into a
          // double in [1, 2). Each call to dis(gen) generates a new random double
          std::cout << dis(gen) << ' ';
      std::cout << '\n';

Possible output:

  1.80829 1.15391 1.18483 1.38969 1.36094 1.0648 1.97798 1.27984 1.68261 1.57326