BigInt/include/functions/random.hpp at 8401447e96aa20ef75c726221073f1050825acfa · faheel/BigInt · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
/*
    ===========================================================================
    Random number generating functions for BigInt
    ===========================================================================
*/

#ifndef BIG_INT_RANDOM_FUNCTIONS_HPP
#define BIG_INT_RANDOM_FUNCTIONS_HPP

#include <random>
#include <climits>

#include "BigInt.hpp"

// when the number of digits are not specified, a random value is used for it
// which is kept below the following:
const size_t MAX_RANDOM_LENGTH = 1000;


/*
    big_random (num_digits)
    -----------------------
    Returns a random BigInt with a specific number of digits.
*/

BigInt big_random(size_t num_digits = 0) {
    std::random_device rand_generator;      // true random number generator

    if (num_digits == 0)    // the number of digits were not specified
        // use a random number for it:
        num_digits = 1 + rand_generator() % MAX_RANDOM_LENGTH;

    std::string random_value = "";
    while (random_value.size() < num_digits)
        random_value += std::to_string(rand_generator());
    if (random_value.size() != num_digits)
        random_value.erase(num_digits);   // erase extra digits

    return BigInt(random_value);
}


#endif  // BIG_INT_RANDOM_FUNCTIONS_HPP