RAND_MAX

 

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Random number distributions Uniform distributions uniform_int_distribution (C++11) uniform_real_distribution (C++11) generate_canonical (C++11) Bernoulli distributions bernoulli_distribution (C++11) binomial_distribution (C++11) negative_binomial_distribution (C++11) geometric_distribution (C++11) Poisson distributions poisson_distribution (C++11) exponential_distribution (C++11) gamma_distribution (C++11) weibull_distribution (C++11) extreme_value_distribution (C++11) Normal distributions normal_distribution (C++11) lognormal_distribution (C++11) chi_squared_distribution (C++11) cauchy_distribution (C++11) fisher_f_distribution (C++11) student_t_distribution (C++11) Sampling distributions discrete_distribution (C++11) piecewise_constant_distribution (C++11) piecewise_linear_distribution (C++11)

 

Defined in header <cstdlib>
#define RAND_MAX /*implementation defined*/

Expands to an integer constant expression equal to the maximum value returned by the function std::rand. This value is implementation dependent. It's guaranteed that this value is at least 32767.

Example

Run this code

#include <climits>
#include <cstdlib>
#include <ctime>
#include <iostream>
 
int main()
{
    / use current time as seed for random generator
    std::srand(std::time(NULL));
 
    std::cout << "RAND_MAX: " << RAND_MAX << '\n'
              << "INT_MAX: " << INT_MAX << '\n'
              << "Random value on [0,1]: "
              << static_cast<double>(std::rand() / RAND_MAX << '\n';
}

Possible output:

RAND_MAX: 2147483647
INT_MAX: 2147483647
Random value on [0,1]: 0.618608

See also

rand	generates a pseudo-random number (function)
srand	seeds pseudo-random number generator (function)
C documentation for RAND_MAX

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