Re: vector<const T(*)> vs. vector<T(*)>

From:
xdotx <fr33.em4il@gmail.com>
Newsgroups:
comp.lang.c++
Date:
Thu, 30 Oct 2008 16:15:42 -0700 (PDT)
Message-ID:
<0a02e10e-991d-40f0-8c92-444c57b154de@w1g2000prk.googlegroups.com>
On Oct 30, 4:04 am, eiji.anonrem...@googlemail.com wrote:

Hi all,

I'm facing some uncertainty with const template arguments.
Maybe someone could explain the general strategy.

#include <vector>

int main(int arc, char** argv)
{
        std::vector<const int> vec;
        const int i = 5;
        vec.push_back(i);
        vec[0] = 4; //const has gone away

        std::vector<const int*> pvec;
        const int* pi = new int(5);
        pvec.push_back(pi);
        *(pvec[0]) = 4; // not possible because const, compile =

error

        return 0;

}

From the first impression, it is not possible to create a vector of
const ints.
But you can do it with pointers.


This is exactly the reason I always use const on the right (correct)
side, especially when dealing with pointers/references.
'const int' is simply a special case way to write: 'int const'. or
with pointers 'const int *' is 'int const *'
Remember: declarations are read right to left from the variable name.
With this in mind the problem is extremely clear:
int const * - poiter to a constant int (pointer can change, integer
cannot)
int * const - constant pointer to an int (integer can change, pointer
cannot)

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