# RAND_MAX

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< cpp‎ | numeric‎ | random

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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