CODEWITHSUNDEEP
c++classtypedef
tpg2114
tpg2114

Reputation: 15100

Typedefs inside a class

Let's say I have a class with an expensive constructor, and let's say I don't need to create the constructor because it's "simple". Inside the class, I want to put a typedef. All together, it looks like:

class Expensive {
public:
    typedef double data_type;
    data_type data[100000][100000];
};

Now, in my calling code, if I do:

Expensive::data_type singleValue;

is that going to create a temporary instance of Expensive and allocate all that space for the data just to get access to the typedef?

Upvotes: 1

Views: 2614

Answers (2)

Lightness Races in Orbit
Lightness Races in Orbit

Reputation: 385144

No; you are accessing what is effectively a static member of the class. No instance is created, and thus no huge huge array.

Upvotes: 0

pmr
pmr

Reputation: 59811

Simply put: No. The operation has no runtime effect whatsoever. Even just declaring a double is not guaranteed to have any effect at runtime as along as you are not using it ;)

Upvotes: 3

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