CODEWITHSUNDEEP
c++
Gerard McCann
Gerard McCann

Reputation: 41

Is it possible to use cin when using allocate to construct a string?

I'm reading up on using allocators and one of the exercises asks to use an allocator to read user input from cin. Right now I create the string using a default constructor then read into the string, but I want to know if its possible to directly create the string with the input from cin?

Current Code:

int n = 1;
std::allocator<std::string> alloc;
auto p = alloc.allocate(n);
auto q = p;
alloc.construct(q);
std::cin >> *q;

Ideally:

alloc.construct(q, input from cin);

Upvotes: 2

Views: 77

Answers (1)

R Sahu
R Sahu

Reputation: 206567

Use of

std::cin >> *q;

does not look like a burden to me. I am not sure what's the motivation for wanting to use:

alloc.construct(q, input from cin);

Having said that, you can define a helper function.

template <typename T> T read(std::istream& in)
{
   T t;
   in >> t;
   return t;
}

Use it as:

int n = 1;
std::allocator<std::string> alloc;
auto p = alloc.allocate(n);
auto q = p;
alloc.construct(q, read<std::string>(std::cin));

Here's a working demo.

Upvotes: 3

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