How to initialize a vector of pointers

Question

I am working on a C++ program, and I need to initialize a vector of pointers. I know how to initialize a vector, but if someone could show me how to initialize it as a vector filled with pointers that would be great!

Check out http://stackoverflow.com/questions/258871/how-to-use-find-algorithm-with-a-vector-of-pointers-to-objects-in-c to see vectors in use. — eppdog, Feb 01 '12 at 04:15
also http://stackoverflow.com/questions/817263/is-it-possible-to-create-a-vector-of-pointers — eppdog, Feb 01 '12 at 04:16

Ben Voigt · Accepted Answer · 2013-04-21T14:15:41.730

30

A zero-size vector of pointers:

std::vector<int*> empty;

A vector of NULL pointers:

std::vector<int*> nulled(10);

A vector of pointers to newly allocated objects (not really initialization though):

std::vector<int*> stuff;
stuff.reserve(10);
for( int i = 0; i < 10; ++i )
    stuff.push_back(new int(i));

Initializing a vector of pointers to newly allocated objects (needs C++11):

std::vector<int*> widgets{ new int(0), new int(1), new int(17) };

A smarter version of #3:

std::vector<std::unique_ptr<int>> stuff;
stuff.reserve(10);
for( int i = 0; i < 10; ++i )
    stuff.emplace_back(new int(i));

edited Apr 21 '13 at 14:15

answered Feb 01 '12 at 04:14

Ben Voigt

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Boo for exception unsafety! :-) – Kerrek SB Feb 01 '12 at 05:06
`emplace_back` doesn't buy you anything with scalar types such as pointers. – fredoverflow Feb 01 '12 at 05:33
2

@FredOverflow: `unique_ptr`'s constructor is explicit, so you either need to use `emplace_back` or `stuff.push_back(std::unique_ptr(new int(i)));`. Between the two, `emplace_back` is much cleaner. – James McNellis Feb 01 '12 at 07:12
1

@JamesMcNellis I stand corrected. – fredoverflow Feb 01 '12 at 13:47

How to initialize a vector of pointers

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