C++如何使用lambda模板函数做参数

[Fenice]

#include <iostream>
#include <functional>

template <typename T>
void Swap(T *a, T *b) {
    T tmp = *a;
    *a = *b;
    *b = tmp;
}

template <typename T>
int partition(T array[], int low, int high, const std::function<int(T, T)> &cmp) {
    int i = low - 1;
    T x = array[high];
    for (int j = low; j < high; j++) {
        if (cmp(array[j], x)) {
            i++;
            Swap(array[j], array[i]);
        }
    }
    array[i + 1] = x;
    return i + 1;
}

template <typename T>
void quicksort(T array[], int low, int high, const std::function<int(T, T)> &cmp) {
    if (low < high) {
        int mid = partition(array, low, high, cmp);
        quicksort(array, low, mid - 1, cmp);
        quicksort(array, mid + 1, high, cmp);
    }
}

int main() {
    std::cout << "Hello, World!" << std::endl;
    int arr[] {5, 3, 9, 1, 6, 2};
    quicksort(arr, 0, 5, [](int a, int b) -> int {
       return a < b;
    });
    for(auto item: arr) {
        std::cout << item << "  ";
    }
    std::cout << std::endl;
    return 0;
}

编译报错：

E:\Project\DesignPattern\main.cpp: In function 'int main()':
E:\Project\DesignPattern\main.cpp:39:6: error: no matching function for call to 'quicksort(int [6], int, int, main()::<lambda(int, int)>)'
});
^
E:\Project\DesignPattern\main.cpp:26:6: note: candidate: template<class T> void quicksort(T*, int, int, const std::function<int(T, T)>&)
void quicksort(T array[], int low, int high, const std::function<int(T, T)> &cmp) {
^
E:\Project\DesignPattern\main.cpp:26:6: note: template argument deduction/substitution failed:
E:\Project\DesignPattern\main.cpp:39:6: note: 'main()::<lambda(int, int)>' is not derived from 'const std::function<int(T, T)>'
});
^
main中quicksort中定义的lambda函数与std::function<int(T,T)>不匹配，如何能让std::function<int(T,T> &cmp接受那个lambda函数参数呢？

[背西风酒旗]

swap函数的形参应该用引用吧！后面的函数Swap(array[j], array[i]);明显传递的是值而不是指针

[ri_aje]

改成这样，其它的以此类推。

template <typename T, typename F>
void quicksort(T array[], int low, int high, F const& cmp);

[ztenv]

你把模板去掉试试

[Fenice]

引用 1 楼 ri_aje 的回复:

改成这样，其它的以此类推。

template <typename T, typename F>
void quicksort(T array[], int low, int high, F const& cmp);

解决了，谢谢！