unique_ptr with deleter

1
votes

I am trying to use std::unique_ptr with deleter. This is my code:

template<class T>
struct Deleter
{
    void operator()(T* p) 
    {
        delete[] p;
    }
};

void Test()
{
    vector<unique_ptr<char>> v;

    for(size_t i = 0; i < 5; ++i)
    {
        char* p = new char[10];
        sprintf(p, "string %d", i);
        v.push_back( unique_ptr<char, Deleter<char>>(p) );  // error is here
    }
}

error C2664: 'void std::vector<_Ty>::push_back(std::unique_ptr &&)' : cannot convert parameter 1 from 'std::unique_ptr<_Ty,_Dx>' to 'std::unique_ptr<_Ty> &&'

Compiler: VC++ 2012. How can I fix this? My goal is to use unique_ptr with custom deleter which calls delete[] instead of default delete.

2
c++smart-pointersunique-ptr
Any reason you're not using vector<string> or vector<array<char>>? – Luchian Grigore

2 Answers

8
votes

There's no need, since unique_ptr knows about arrays already!

std::unique_ptr<char[]> p(new char[10]);
sprintf(p.get(), "...");

The array specialization even gives you array-like access à la p[0] = 'a'; etc.

Your vector type has to match, of course: std:vector<std::unique_ptr<char[]>>

4
votes

unique_ptr<char> and unique_ptr<char, Deleter<char>> are two different types. Therefore, you should declare your vector as:

vector<unique_ptr<char, Deleter<char>>> v;