c++ - 尝试使用 random_device、mt19937 和 uniform_int_distribution 时出现大量编译器错误

Question

我最近才开始学习 C++，所以我在调试程序时遇到了麻烦。

我想生成随机数。经过一些谷歌搜索后，似乎一种方法是按照

#include <random>

std::mt19937 rng;
std::uniform_int_distribution<int> distribution;

int main()
{
    rng(std::random_device()());
    distribution(0, 10);
}

但是，当我用 g++ -std=c++14 test.cpp 编译它时，我得到了这些错误:

test.cpp: In function ‘int main()’:
test.cpp:8:31: error: no match for call to ‘(std::mt19937 {aka std::mersenne_twister_engine<unsigned int, 32u, 624u, 397u, 31u, 2567483615u, 11u, 4294967295u, 7u, 2636928640u, 15u, 4022730752u, 18u, 1812433253u>}) (std::random_device::result_type)’
     rng(std::random_device()());
                               ^
In file included from /usr/include/c++/5/random:49:0,
                 from test.cpp:1:
/usr/include/c++/5/bits/random.h:546:7: note: candidate: std::mersenne_twister_engine<_UIntType, __w, __n, __m, __r, __a, __u, __d, __s, __b, __t, __c, __l, __f>::result_type std::mersenne_twister_engine<_UIntType, __w, __n, __m, __r, __a, __u, __d, __s, __b, __t, __c, __l, __f>::operator()() [with _UIntType = unsigned int; unsigned int __w = 32u; unsigned int __n = 624u; unsigned int __m = 397u; unsigned int __r = 31u; _UIntType __a = 2567483615u; unsigned int __u = 11u; _UIntType __d = 4294967295u; unsigned int __s = 7u; _UIntType __b = 2636928640u; unsigned int __t = 15u; _UIntType __c = 4022730752u; unsigned int __l = 18u; _UIntType __f = 1812433253u; std::mersenne_twister_engine<_UIntType, __w, __n, __m, __r, __a, __u, __d, __s, __b, __t, __c, __l, __f>::result_type = unsigned int]
       operator()();
       ^
/usr/include/c++/5/bits/random.h:546:7: note:   candidate expects 0 arguments, 1 provided
test.cpp:9:23: error: no match for call to ‘(std::uniform_int_distribution<int>) (int, int)’
     distribution(0, 10);
                       ^
In file included from /usr/include/c++/5/random:49:0,
                 from test.cpp:1:
/usr/include/c++/5/bits/random.h:1768:2: note: candidate: template<class _UniformRandomNumberGenerator> std::uniform_int_distribution<_IntType>::result_type std::uniform_int_distribution<_IntType>::operator()(_UniformRandomNumberGenerator&) [with _UniformRandomNumberGenerator = _UniformRandomNumberGenerator; _IntType = int]
  operator()(_UniformRandomNumberGenerator& __urng)
  ^
/usr/include/c++/5/bits/random.h:1768:2: note:   template argument deduction/substitution failed:
test.cpp:9:23: note:   candidate expects 1 argument, 2 provided
     distribution(0, 10);
                       ^
In file included from /usr/include/c++/5/random:49:0,
                 from test.cpp:1:
/usr/include/c++/5/bits/random.h:1773:2: note: candidate: template<class _UniformRandomNumberGenerator> std::uniform_int_distribution<_IntType>::result_type std::uniform_int_distribution<_IntType>::operator()(_UniformRandomNumberGenerator&, const std::uniform_int_distribution<_IntType>::param_type&) [with _UniformRandomNumberGenerator = _UniformRandomNumberGenerator; _IntType = int]
  operator()(_UniformRandomNumberGenerator& __urng,
  ^
/usr/include/c++/5/bits/random.h:1773:2: note:   template argument deduction/substitution failed:
test.cpp:9:23: note:   cannot convert ‘10’ (type ‘int’) to type ‘const std::uniform_int_distribution<int>::param_type&’
     distribution(0, 10);
                       ^

我对 random_device、mt19937 和 uniform_int_distribution 做了一些研究，根据我有限的知识，我似乎正确地使用了所有东西.我基本上还在 SO 上复制粘贴了其他答案中的代码，所以看起来代码应该可以工作。更改代码的上下文是否破坏了什么？

Answer 1

您混淆了设备、生成器和分配器的概念。尽量把每件事分开；然后它会变得简单。

#include <random>
#include <iostream>

int main()
{
    std::random_device rd;
    std::mt19937 gen(rd());
    std::uniform_int_distribution<> dis(1, 200);
    for (int n = 0; n < 10; ++n) {
        std::cout << dis(gen) << ' ';
    }
    std::cout << '\n';
}