Question

#include <iostream>
using std::cout;
using std::cin;

struct Array {
    int *A;
    int size;
    int length;
};

void display(Array *arr) {
    for(int i = 0; i < arr->length; i++) {
        cout << arr->A[i] << "\t";
    }
    cout << "\n";
}

Array* merge(Array *arr, Array *brr) {
    Array *crr;
    crr->length = 0;
    crr->size = arr->length + brr->length;
    crr->A = new int[crr->size];
    int i, j, k; i=j=k=0;
    while(i < arr->length && j < brr->length) {
        if (arr->A[i] < brr->A[j]) {
            crr->A[k++] = arr->A[i++];
        } else {
            crr->A[k++] = brr->A[j++];
        }
    }
    for(;i < arr->length; i++) {
        crr->A[k++] = arr->A[i];
    }
    for(;j < brr->length; j++) {
        crr->A[k++] = brr->A[j];
    }
    crr->length = arr->length + brr->length;
    return crr;
}

int main() {
    Array arr1 = {{ 2, 6, 10, 15, 25}, 10, 5};
    Array arr2 = {{ 3, 4, 7, 18, 20}, 10, 5};
    Array *arr3;
    arr3 = merge(&arr1, &arr2);
    display(arr3);
}

编译此命令会给我这个错误。正确的方法是什么？

$ g++ -o merge_arrays merge_arrays.cpp 
merge_arrays.cpp: In function ‘int main()’:
merge_arrays.cpp:42:42: error: cannot convert ‘<brace-enclosed initializer list>’ to ‘int*’ in initialization
   42 |  Array arr1 = {{ 2, 6, 10, 15, 25}, 10, 5};
      |                                          ^
merge_arrays.cpp:43:41: error: cannot convert ‘<brace-enclosed initializer list>’ to ‘int*’ in initialization
   43 |  Array arr2 = {{ 3, 4, 7, 18, 20}, 10, 5};
      |                                         ^

我要在声明struct Array的同一位置对其进行初始化。这不是推荐的方法吗？我阅读了许多stackoverflow答案，建议我在声明它们的同一位置初始化数组。这正是我在这里所做的。所以有点困惑。任何帮助将不胜感激。

Answer 1

拥有原始指针，它将是：

Array arr1 = {new int[10]{ 2, 6, 10, 15, 25}, 10, 5};

但是您的课程不遵守3/5/0规则和泄漏资源。

但是标准已经提供了std::vector来处理集合和std::merge：

void display(const std::vector<int>&v) {
    for(int e : v) {
        cout << e << "\t";
    }
    cout << "\n";
}

std::vector<int> merge(const std::vector<int>&v1, const std::vector<int>&v2)
{
    std::vector<int> res(v1.size() + v2.size());

    std::merge(v1.begin(), v1.end(), v2.begin(), v2.end(), res.begin());
    return res;
}

int main() {
    std::vector arr1 = { 2, 6, 10, 15, 25};
    std::vector arr2 = { 3, 4, 7, 18, 20};
    auto arr3 = merge(arr1, arr2);
    display(arr3);
}

Demo

初始化时无法将“ <括号括起来的初始化程序列表>”转换为“ int *”

1 个答案: