Vector Initializer_list - c++11

Question

I am trying to implement a vector using my own class so I can not do the initialiser list part
# include <iostream>
# include <exception>
# include<initializer_list>
template <class T>
class vector {
public:
T* a;
T n;
int pos, c;
vector() { a = 0; n = 0; }
vector(T n) : n(n) { a = new T[n]; }
vector(std::initializer_list <vector> l) {
a = new T[int(sizeof(l))];
for (int f : l)
*(a + f) = l.begin() + f;
}
void push_back(T k) {
int i = k;
*(a + n) = k;
}
vector& operator= (vector&& th) {
this->a = th.a;
th.a = nullptr; return (*this);
}
vector& operator=(vector& k)
{
this->a = k.a;
return(*this);
}
int size() { return n; }
void pop_back() { *(a + n) = nullptr;
n--;
}
void resize(int c) {
delete a;
n = c;
a = new T[c];
}
T operator[](int pos) {
if (pos > sizeof(a))
std::cout << "out of range";
else return *(a + pos);
}
};
int main() {
vector<int> a(10);
vector<char>b{ 'w','b','f','g' };
getchar();
return 0;
}
I am just trying to use pointer offset notation to take the initializer list items into the dynamic array but I get errors VS 17 IDE
Severity Code Description Project File Line Suppression
Error C2440 '=': cannot convert from 'const _Elem *' to 'T'
Error C2440 'initializing': cannot convert from 'const _Elem' to 'int'

Answer 1

Hello Nimrod!
#include <iostream>
#include <exception>
#include <initializer_list>
// normally people don't place a space between '#' and 'include'
template <class T>
class vector {
public:
T* a;
int n;
// probably it is length the vector
// change T to int
int pos, c;
vector() {
a = nullptr;
// do not use '0' to instruct null pointer
n = 0;
}
vector(int n): n(n) { a = new T[n]; }
vector(std::initializer_list<T> l) {
a = new T[l.size()];
// redundant force cast from size_t to int
for (int i = 0; i < l.size(); i++) {
a[i] = l.begin()[i];
}
// for (int f : l) # it seems that you wrote JavaScript before?
// *(a + f) = l.begin() + f;
}
void push_back(T k) {
// assigns "T k" to "int i"? it's confusing
// int i = k;
// *(a + n) = k;
}
// probably still many problems
vector& operator=(vector&& th) {
this->a = th.a;
th.a = nullptr;
return (*this);
}
vector& operator=(vector& k) {
this->a = k.a;
return(*this);
}
int size() { return n; }
void pop_back() { *(a + n) = nullptr;
n--;
}
void resize(int c) {
delete a;
n = c;
a = new T[c];
}
T operator[](int pos) {
if (pos > sizeof(a))
std::cout << "out of range";
else return *(a + pos);
}
};
int main() {
vector<int> a(10);
vector<char>b{ 'w','b','f','g' };
getchar();
return 0;
}
You still need more practice. XP
In your context of code, template variable for initializer_list should be T rather than int.
Range for loop with initializer_list<T> will fetch the values
in the list. Therefore it should belong to T.