pointer to vector problem

[naveen2525]

ive created a vector of vector and initialized like this
vector<vector<double>*>* vec1= new vector<vector<double>*>;
for(size_t t =0 ;t<500 ;t++ )
{
vector<double>* v = new vector<double>;
vec1->pushback(v);
}

now can i assign like this ??
vector<vector<double>*>* vec2 = vec2 ;
in my program it worked fine and when i rebuild im getting error ->

Error 33 error C2440: 'initializing' : cannot convert from 'std::vector<_Ty>' to 'std::vector<_Ty> '

[giblit]

May I ask why you are using pointers for this?

[xismn]

Do you really need a vector pointer of vector pointers? What are you trying to achieve?

[naveen2525]

yes i need pointers because values or not fixed it is more than 500
10000+ values need to be inserted

[MiiNiPaa]

yes i need pointers because values or not fixed it is more than 500

Vector is dynamically sized so large and unknown amounts is not a problem.

10000+ values need to be inserted

Vector stores it values in heap, so it will be no problem with that too.
Read about reserve() method. It will help with perfomance.

[naveen2525]

thanks

now ive used pointer everywhere in my project and i dont want to modify that one but wanted to assign it some other
i want to assign this -> vector<vector<double>*>* vec1 to vector<vector<double>> is it possible ???

[giblit]

use the copy constructor.

std::vector<std::vector<double>* >* vec2(vec1);

[naveen2525]

i wanted to copy pointer values vector<vector<double>*>* vec1 to
vector<vector<double>> vec2

[giblit]

Oh I didn't even notice because your original code had pointers. Anyways why would you want to do that? Doesn't really make sense to me. The only way I can think of though is to iterate with something like:

for(const auto &it:vec1)
{
    vec2.push_back(std::vector<double>());
    for(const auto &it2:it)
    {
        vec2.back().push_back(it2);
    }
}

There is probably other ways but I don't think any of them will be to pretty.

[naveen2525]

okk
but in my project all vector pointers are used i dont know y
cant we use simple vectors for that
can u tell me diff between vector<vector<double>*>* and vector<vector<double>> in terms of memory and etc

[giblit]

One of them is a pointer to a container of containers full of pointers and the other is a container full of containers of objects. I would really only use pointers if the data types are large and not built-in types like doubles/ints/chars ect..

I think you should read up on pointers and STL containers before using them.

http://www.cplusplus.com/doc/tutorial/pointers/
http://www.cplusplus.com/reference/stl/

[naveen2525]

ok got it
i want to copy vector<vector<double>*>* vec1 from vector<vector<double>*>* vec2 and pass vector<vector<double>*>* vec1 to a function

and i need vec1 and vec2 to be present
ex : func(vector<vector<double>*>* , vector<string>);