STL container assignment and const pointers

Question

This compiles:

int* p1;
const int* p2;
p2 = p1;

This does not:

vector v1;
vector v2;
v2 = v1;         


        

Answer 1

Conversion from int* to const int* is built into the language, but vectors of these have no automatic conversion from one to the other.

Answer 2

The issue is not the pointers, but the types of the two vectors. There are no standard conversions between templated types like those of v1 and v2 in your example.

This is perhaps easier to see in the following code:

#include <vector>
using namespace std;

int main() {
    vector <char> cv;
    vector <int> iv;
    cv = iv;    // error
}