Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Welcome To Ask or Share your Answers For Others

Categories

0 votes
315 views
in Technique[技术] by (71.8m points)

c++ - Why does std::array not have an constructor that takes a value for the array to be filled with?

Is the absence of

std::array<T,size>::array(const T& value);

an oversight? It seems mighty useful to me, and dynamic containers (like std::vector) do have a similar constructor.

I am fully aware of

std::array<T,size>::fill(const T& value);

but that is not a constructor, and the memory will be zeroed out first. What if I want all -1's like this guy?

See Question&Answers more detail:os

与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
Welcome To Ask or Share your Answers For Others

1 Reply

0 votes
by (71.8m points)

std::array is, by design, an aggregate, so has no user-declared constructors.

As you say, you could use fill after default constructing. Since it's an aggregate, default construction won't zero the memory, but will leave it uninitialised (if the contained type is trivially initialisable).


与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…
OGeek|极客中国-欢迎来到极客的世界,一个免费开放的程序员编程交流平台!开放,进步,分享!让技术改变生活,让极客改变未来! Welcome to OGeek Q&A Community for programmer and developer-Open, Learning and Share
Click Here to Ask a Question

...