[英]Dynamic generic array overload the subscript operator []?
Hello i want to be able to access index from the subscript operator.您好,我希望能够从下标运算符访问索引。 However i currently get this error:但是我目前收到此错误:
Error C2440 'return': cannot convert from 'T' to 'List<char> &'
I also tried with different things but i dont know how to do it and where this error comes from?我也尝试过不同的东西,但我不知道该怎么做以及这个错误来自哪里? If anyone can check it out i will be thankful.如果有人可以检查出来,我将不胜感激。
The problem is i get this List i dont understand why?问题是我得到这个列表我不明白为什么? Here is the function:这是 function:
List& operator[] (int index) {
return first_cell[index];
}
There is the whole code:有完整的代码:
template<class T>
class List {
private:
T* first_cell = nullptr;
int size = 0; // currently occupied elements
int capacity = 8; // size of the allocated memory
void resize() {
int new_cap = capacity * 2; // increased capacity
T* new_arr = new T[new_cap]; // new arr with new capacity
for (int k = 0; k < size; ++k) {
new_arr[k] = first_cell[k]; // copy data from frist array
}
delete[] first_cell; // remove first array
first_cell = new_arr;
capacity = new_cap;
}
public:
List() {
first_cell = new T[capacity]; // Declare the array in memory
}
List(const List& src)
: size(src.size),
capacity(src.capacity)
{
first_cell = new T[capacity];
std::copy_n(src.first_cell, size, first_cell);
}
List(List&& src)
: first_cell(src.first_cell),
size(src.size),
capacity(src.capacity)
{
src.first_cell = nullptr;
src.size = src.capacity = 0;
}
~List() {
delete[] first_cell;
}
List& operator=(List rhs) {
List temp(std::move(rhs));
std::swap(first_cell, temp.first_cell);
std::swap(size, temp.size);
std::swap(capacity, temp.capacity);
return *this;
}
// ToDo: ADD access operator
List& operator[] (int index) {
return first_cell[index];
}
void push_back(int number) {
if (size == capacity) {
resize();
}
first_cell[size] = number;
++size;
}
int length() {
return size;
}
int first_index_of(int number) {
for (int k = 0; k < size; k++) {
if (number == first_cell[k]) {
return k;
}
}
return -1;
}
void print(char symb) {
for (int k = 0; k < size; ++k) {
std::cout << first_cell[k] << symb;
}
}
};
You are trying to return a single element in the array, so your operator[]
needs to return a reference to the element type, not a reference to the list type:您正在尝试返回数组中的单个元素,因此您的operator[]
需要返回对元素类型的引用,而不是对列表类型的引用:
T& operator[] (int index) {
return first_cell[index];
}
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