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RAND_MAX

From cppreference.com
< cpp‎ | numeric‎ | random
 
 
 
Pseudo-random number generation
Uniform random bit generators
Engines and engine adaptors
Non-deterministic generator
Distributions
Uniform distributions
Bernoulli distributions
Poisson distributions
Normal distributions
Sampling distributions
Seed Sequences
(C++11)
C library
RAND_MAX
 
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.

[edit] Example

#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

[edit] See also

generates a pseudo-random number
(function) [edit]
seeds pseudo-random number generator
(function) [edit]
C documentation for RAND_MAX