How to declare an array and then assign in another line

Question

class c{};

c *ar[2];

ar = {new c, new c}; //error

"Array type is not assignable" How to assign it after declaring it, i want to do that because the class is using that variable so i just want to declare it, create a class and then assign the value, i can't assign before the class because it can't make a new c without defing the class first.

You can't assign to an array, only copy to it or set its element separately. — Some programmer dude
– Some programmer dude, Commented Jul 20, 2017 at 12:15
Read the last part of my comment again... Or use std::array instead. — Some programmer dude
– Some programmer dude, Commented Jul 20, 2017 at 12:18
@ViktorLazic I would suggest you to study a good c++ book. SO is not here to baby spoon everyone. Google is your friend. — KostasRim
– KostasRim, Commented Jul 20, 2017 at 12:25
Sounds like you could benefit from reading one of these C++ books. — Ron
– Ron, Commented Jul 20, 2017 at 12:38

Andriy Tylychko · Accepted Answer · 2017-07-20 13:06:21Z

1

use standard library algorithm generate:

#include <algorithm>
#include <iterator>

class c{};
c* ar[2];
std::generate(std::begin(ar), std::end(ar), [] { return new c; });

edited Jul 20, 2017 at 13:06

answered Jul 20, 2017 at 12:46

Andriy Tylychko

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3 Comments

KABoissonneault Over a year ago

What was wrong with your previous version using std::begin and std::end? It's more readable (from begin to end), and less error prone

Andriy Tylychko Over a year ago

@KABoissonneault: godbolt.org/g/SFeaBh, GCC 7.1 failed, same error: no matching function for call to 'begin(c* [2])' with Clang 4.0, works fine with VS2015 or GCC 4.9, surprised, investigating

KABoissonneault Over a year ago

Try including <iterator>

IlBeldus · Accepted Answer · 2017-07-20 12:28:27Z

0

use a loop:

for(auto i = std::begin(ar);i!=std::end(ar);++i)
    *i = new c;

this will work for (almost) all container classes, not just raw arrays.

answered Jul 20, 2017 at 12:28

IlBeldus

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