Question

我试图创建一个数组，使用某个随机种子（我已经）从0-9生成20个随机数，然后计算生成的随机数的平均值。我已经得到它来执行数组罚款，但是当我去计算随机数的总和时，它会让我回到-16。我已经看了几个不同的其他事情试图帮助他们都有同样的事情我有

for (i = 0; i < SIZE; i++) {
            sum += num[SIZE];}

有人可以指出我在这里做错了什么，或者在程序中的哪个位置？

#include <iostream>
#include <cstdlib>

using namespace std;

int main() // Creates the array
{
    srand(2622); // random seed 

    const int SIZE = 20;
    int num[SIZE], i, sum = 0;  


    for (i = 0; i < 20; i++) {
        cout << rand() % 10 << " : "; // generates random numbers 0-10
    }
        cout << endl;

    for (i = 0; i < SIZE; i++) {
        sum += num[SIZE];

    }
        cout << sum << endl; 


    return 0;

}

Answer 1

你在这里失踪 -

sum += num[SIZE]; should be sum += num[i];

#include <iostream>
#include <cstdlib>

using namespace std;

int main() // Creates the array
{
    srand(2622); // random seed 

    const int SIZE = 20;
    int num[SIZE], i, sum = 0;  


    for (i = 0; i < 20; i++) {
        num[i] = rand() % 10  ;
        cout << num[i] << " : "; // generates random numbers 0-10
    }
        cout << endl;

    for (i = 0; i < SIZE ; i++ ) {
        sum += num[i];

    }
        cout << sum << endl; 


    return 0;

}

Answer 2

仅仅是为了阐述，这里是使用c ++ 14和习惯使用标准库的相同程序。

#include <iostream>
#include <numeric>
#include <random>
#include <functional>

using namespace std;

template<class Iter>
std::ostream& emit_range(std::ostream& os, Iter first, Iter last,
                         const char* inter_sep = " : ",
                         const char* terminator = "\n")
{
    auto sep = "";
    while (first != last) {
        os << sep << *first;
        ++first;
        sep = inter_sep;
    }
    return os << terminator;
}

int main() // Creates the array
{
    // function object to create a pre-seeded pseudo-random sequence
    auto next_number = [eng = std::default_random_engine(2622),
                 dist = std::uniform_int_distribution<int>(0, 9)]() mutable
    {
        return dist(eng);
    };

    constexpr int SIZE = 20;
    int num[SIZE];

    // generate the random numbers
    std::generate(std::begin(num), std::end(num), next_number);

    // compute the sum
    auto sum = std::accumulate(std::begin(num), std::end(num), 0,
                               std::plus<>());

    // compute the average
    auto average = double(sum) / SIZE;

    // print results    
    emit_range(cout, std::begin(num), std::end(num));
    cout << sum << endl;
    cout << average << endl;


    return 0;

}

结果：

1 : 9 : 6 : 6 : 3 : 0 : 3 : 6 : 7 : 1 : 7 : 2 : 1 : 8 : 0 : 0 : 2 : 6 : 1 : 9
78
3.9

找到随机数组的平均值

2 个答案: