C++ 整数数组转换和操作

Question

所以我有一个任务要

• 输入一个数组，
• 计算它的偶数(正数和负数)，
• 计算所有偶数的总和#
• 在程序必须输出一个转换后的数组后，其中每个偶数 # 都变成它前面所有数字的总和(** 在原始数组 ** 中):arr[i] = 1, 2, 3, 4, 5, 6; -> array[i] = 1, 1, 3, 6, 5, 15

所以我是这样尝试的，但它一直工作到第 5 个元素，之后它开始输出一些看起来很奇怪的 #s。我该怎么办？？？

#include <iostream>
#include <climits>
#include <cmath>
#include <cstdlib>
#include <locale>
#include <algorithm>

using namespace std;

int main()
{
    srand((unsigned)time(NULL));
    int n, i, k = 0;
    int sum;
    int S = 0;
    cout << "What size array would you like:" << endl;
    cout << "n = ";
    cin >> n;
    int* A = new int[n];
    sum = 0;
    cout << "Input elements: ";
    for (i = 0; i < n; i++) cin >> A[i];
    for (int i = 0; i < n; i++)
    {
        cout << A[i] << " ";
    }
    cout << endl;
    cout << endl;
    for (int i = 0; i < n; i++)
    {
        if (A[i] % 2 == 0) {
            k = k + 1;
            sum += A[i];
        }
    }
    cout << "Ampount of even numbs: " << k << endl << endl;
    cout << "Sum of even numbs: " << sum << endl << endl;
    cout << "New array: " << endl;
    for (int i = 0; i < n; i++)
    {
        if (abs(A[i]) % 2 == 0)
        {
            for (int j = 0; j < i; j++)
            {
                S += A[j];
            }
            A[i] = S;
        }
    }

    for (int i = 0; i < n; i++)
    {
        cout << A[i] << " ";
    }
    cout << endl;
    cout << endl;
}

Answer 1

好吧，你说的是 C++ 和“有趣”，所以这里有一个更 C++ 的方法来给这只猫换皮。 .

#include <iostream>
#include <algorithm>
#include <vector>
#include <numeric>
using namespace std;    

int main() {
    vector<int> v = {1,2,3,4,5,6};
    const auto isEven = [](int x){return x%2==0;};
    const auto print = [](const int& n) { cout << " " << n; };

    cout << "Before: "; for_each(v.begin(), v.end(), print); cout << endl;
    cout << "Num Even: " << count_if(v.begin(), v.end(), isEven) << endl;
    cout << "Sum Even: " << accumulate(v.begin(), v.end(), 0, [isEven](auto acc, int e) { return acc + (isEven(e) ? e : 0); }) << endl;
    // I'm not guru enough for Jarod42s c++20 voodoo 🤯nor is IDEONE 😉
    int b=0;
    vector<int> v2;
    for (auto& x : v) {
        isEven(x) ? v2.push_back(b) : v2.push_back(x);
        b+=x;
    }
    cout << "Transformed: "; for_each(v2.begin(), v2.end(), print); cout << endl;

    return 0;
}

在这里尝试 https://ideone.com/jDjoeB