为什么我得到数组size（）的错误，如何声明boost :: threads数组？

Question

我收到此错误。 该功能应该执行mergeSort，但最后没有进行合并。 稍后我会做，但是我想确保它不会在最后进行最终合并。

编辑：我必须使用#include boost / thread.hpp，因为我学校使用的Linux服务器没有c ++ 11

multi.cpp: In function 'int main()':
multi.cpp:116:29: error: request for member 'size' in 'data', which is of non-class type 'int [1000000]'
multi.cpp:116:54: error: request for member 'size' in 'data', which is of non-class type 'int [1000000]'
multi.cpp:117:32: error: expected primary-expression before 't1'
multi.cpp:117:32: error: expected ';' before 't1'
multi.cpp:120:31: error: request for member 'size' in 'data', which is of non-class type 'int [1000000]'

这是我的代码。 我很确定我的错误是由于我不知道如何设置线程数组而引起的。 我可以等一个线程完成后再向阵列添加另一个线程吗？

#include <cstdlib>
#include <iostream>
#include <boost/thread.hpp>
using namespace std;

void merge(int arr[], int l, int m, int r);
void mergeSort(int arr[], int l, int r);
bool is_sorted(int* data, int size);
bool is_sorted(int* data, int size) {
    for(int i = 0; i < size - 1; ++i)
        if(data[i] > data[i+1])
            return false;

    return true;
}

void merge(int arr[], int l, int m, int r)
{
    int i, j, k;
    int n1 = m - l + 1;
    int n2 =  r - m;

    /* create temp arrays */
    int L[n1], R[n2];

    /* Copy data to temp arrays L[] and R[] */
    for (i = 0; i < n1; i++)
        L[i] = arr[l + i];
    for (j = 0; j < n2; j++)
        R[j] = arr[m + 1+ j];

    /* Merge the temp arrays back into arr[l..r]*/
    i = 0; // Initial index of first subarray
    j = 0; // Initial index of second subarray
    k = l; // Initial index of merged subarray
    while (i < n1 && j < n2)
    {
        if (L[i] <= R[j])
        {
            arr[k] = L[i];
            i++;
        }
        else
        {
            arr[k] = R[j];
            j++;
        }
        k++;
    }

    /* Copy the remaining elements of L[], if there
       are any */
    while (i < n1)
    {
        arr[k] = L[i];
        i++;
        k++;
    }

    /* Copy the remaining elements of R[], if there
       are any */
    while (j < n2)
    {
        arr[k] = R[j];
        j++;
        k++;
    }
}
void mergeSort(int arr[], int l, int r)
{
    if (l < r)
    {
        // Same as (l+r)/2, but avoids overflow for
        // large l and h
        int m = l+(r-l)/2;

        // Sort first and second halves
        mergeSort(arr, l, m);
        mergeSort(arr, m+1, r);

        merge(arr, l, m, r);
    }
}

struct my_sort{
    public:
        void operator()()
        {
            mergeSort(arr, l, r);
        }
        my_sort(){}
        my_sort(int array[], int left, int right)
        {
            arr = array;
            l = left;
            r = right;
        }


    private:
        int* arr;
        int l;
        int r;

};

int main() {
    int data[1000000];
    for(int i = 0; i < 1000000; i++)
        data[i] = rand();

    unsigned threads = boost::thread::hardware_concurrency();
    boost::thread threading[threads];
    for(int i = 0; i < threads; i++)
    {
        my_sort m1(data, i * data.size()/threads, i * data.size()/threads - 1);
        threading[i] = boost::thread t1{m1};
    }

    cout << is_sorted(data, data.size()-1);

    return 0;
}

Answer 1

multi.cpp:116:29: error: request for member 'size' in 'data', which is of non-class type 'int [1000000]'
...
multi.cpp:120:31: error: request for member 'size' in 'data', which is of non-class type 'int [1000000]'

类型int[1000000]没有size方法。 它是原始类型。 使用sizeof或更好的std::vector 。 （当您可以访问C ++ 11时，可以使用std::array 。）

multi.cpp:117:32: error: expected primary-expression before 't1'
multi.cpp:117:32: error: expected ';' before 't1'

...

threading[i] = boost::thread t1{m1};

这是语法错误。 您是否要在表达式中定义变量？