CODEWITHSUNDEEP
c++
tez
tez

Reputation: 5300

When does copy constructor get called

I studied that during initialization of object, for example 

string s = "Hello world";

If RHS is implicitly convertible to LHS type object, then Copy Constructor would be called. But I have a friend who is pretty sure that constructor which takes char pointer as an argument would be called.But I told him that constructor with charpointer would be called only in cases as below

string s("Hello world");

Is that correct?

Upvotes: 2

Views: 453

Answers (2)

K-ballo
K-ballo

Reputation: 81349

Doing

string s = "Hello world";

is equivalent to

string s( string( "Hello world" ) );

so both the constructor taking char const* and the copy-constructor are called. However, the standard allows copy-elision where the copy-constructor call is elided (not done).

Upvotes: 7

Luchian Grigore
Luchian Grigore

Reputation: 258608

Yes and no. Both are called.

string s = "Hello world";

This is copy initialization. It calls the conversion constructor and constructs a temporary string from "Hellow world" and then uses that temporary with the copy constructor to construct s. (subject to optimizations)

string s("Hello world");

Is direct initialization and calls the conversion constructor directly, constructing s from "Hello world".

Upvotes: 3

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