I have such array:
我有这样的数组:
long my_array_left[n][2];
I wrote comparator function for it, which takes array of two elements and sort by first element of array:
我为它编写了比较器函数，它取两个元素的数组，按数组的第一个元素排序:
struct sort_left {
bool operator()(const long &left[2], const long &right[2]) {
return left[0] < right[0];
}
}
Then I use library function std::sort for sorting my_array_left[n][2]
然后我使用库函数std::sort对my_array_left[n][2]进行排序
sort(begin(my_array_left), end(my_array_left), sort_left());
But I have an error: parameter type mismatch: Incompatible pointer types 'long **' and 'long[2]*'.
但是我有一个错误:参数类型不匹配:不兼容的指针类型“long **”和“long[2]*”。
How can I overcome it?
我如何克服它?
1 个解决方案
#1
4
Your immediate problem can be fixed by having a comparator that actually takes references to arrays instead of references to pointers:
你当前的问题可以通过一个比较器来解决，这个比较器实际上是引用数组而不是引用指针:
struct sort_left {
bool operator()(const long (&left)[2], const long (&right)[2]) {
return left[0] < right[0];
}
};
But since you can't assign an array to another array, your code won't compile anyway.
但是由于无法将数组赋值给另一个数组，所以代码也无法编译。
You can avoid this by using std::array:
可以通过使用std:::array来避免这一点:
array<array<long, 2>, N> arr{};
sort(arr.begin(), arr.end());
The added benefit is that operator< is automatically defined if array's value_type that defines it.
附加的好处是，如果数组的value_type定义了操作符，那么操作符 <是自动定义的。< p>
#1
4
Your immediate problem can be fixed by having a comparator that actually takes references to arrays instead of references to pointers:
你当前的问题可以通过一个比较器来解决，这个比较器实际上是引用数组而不是引用指针:
struct sort_left {
bool operator()(const long (&left)[2], const long (&right)[2]) {
return left[0] < right[0];
}
};
But since you can't assign an array to another array, your code won't compile anyway.
但是由于无法将数组赋值给另一个数组，所以代码也无法编译。
You can avoid this by using std::array:
可以通过使用std:::array来避免这一点:
array<array<long, 2>, N> arr{};
sort(arr.begin(), arr.end());
The added benefit is that operator< is automatically defined if array's value_type that defines it.
附加的好处是，如果数组的value_type定义了操作符，那么操作符 <是自动定义的。< p>