Initializes an object from another object
Questions tagged [copy-initialization]
52 questions
4
votes
2 answers
copy initialization : why move or copy constructor was not called even if copy-elision is turned off?
My question is different because I may "know" copy-elision. I am learning copy initialization. However,the following code confused me because I have already turned off the copy-elision using -fno-elide-contructors -O0 option.
#include…
Han XIAO
- 1,148
- 9
- 20
4
votes
1 answer
Why is a conversion operator not called when using initialization syntax, and why does the clang error message seem wrong?
I have the following code, which constructs one object t2 using a explicit conversion constructor, which performs an implicit conversion of t1. This is expected, and is described in The C++ Programming Language, in section 11.4.1 of the 3rd…
peter
- 43
- 2
- 4
4
votes
1 answer
Why can't I copy-initialize a stringstream from a string?
The following code fails in GCC, Clang and Visual Studio:
#include
#include
int main() {
std::string s = "hello"; // ok, copy-initialization
std::stringstream ss1(s); // ok, direct-initialization
std::stringstream ss2…
Nikolai
- 3,053
- 3
- 24
- 33
3
votes
1 answer
Why here template Vector3 cannot convert to Vector3?
It seems quite weird. Here you can see the error message is that a convert happens between one type and it fails. If I remove the explicit modifier from Vector3's copy constructor it is fine, no error. Could someone explain why? I'm…
Young_cun_yi_ba
- 57
- 2
3
votes
1 answer
Is copy initialization identical to copy initialization of a copy?
The following two code segments presents the task of initializing variable b as a copy of a. The first code segment initializes the variable using copy initialization (initialization using =). Assume class Apple is simply defined as an empty…
Taras Palczynski
- 189
- 1
- 10
3
votes
1 answer
Issues about the copy-initialization of reference type
#include
struct Data{};
struct Test{
Test() = default;
Test(Data){}
};
int main(){
Data d;
Test const& rf = d;
}
Consider the above code, The standard says:
Otherwise:
5.2.2.1 If T1 or T2 is a class type and T1 is not…
xmh0511
- 7,010
- 1
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- 36
3
votes
1 answer
Confused about c++ constructor deletion
This is my class
class A {
public:
A(int);
A(A const&) = delete;
A& operator=(const A& a) = delete;
// etc.
};
In another file I can call the constructor like this:
auto foo = A(123);
That resolves to the copy constructor and not the…
Allie
- 57
- 2
3
votes
2 answers
What actually happens when copy initializing in C++?
Consider the following code:
#include
using namespace std;
class A{
public:
A()=default;
A(int a){cout<<"A(int) called"<
sakugawa
- 117
- 5
3
votes
2 answers
removing the const in copy constructor
This is what I did originally.
class A
{ public:
A() { std::cout << "\ndefault constructor"; }
A(const A&) { std::cout << "\ncopy constructor"; }
A(int) { std::cout << "\nconversion constructor"; }
};
A a0; …
Dick Chow
- 31
- 2
3
votes
2 answers
conversion operator bypasses constructor of the derived type and skips to copy-initialization of the base type?
There is something wrong with how the conversion operator behaves in the following code:
struct A{
A(){};
A(const A &) = delete;
};
struct B : A{
B(const B & x){};
B(int x){};
};
struct C{
operator B() {
return B(1);
…
Alexander Shekhovtsov
- 302
- 1
- 2
- 10
3
votes
2 answers
C++(11): When to use direct or copy initialization if both are perfectly fine
Before the shouts for duplicate begin: I am aware that the following question (and some others) are quite related to this one:
Is there a difference in C++ between copy initialization and direct initialization?
The answers in this question perfectly…
gexicide
- 38,535
- 21
- 92
- 152
3
votes
3 answers
Difference between $a=&$b , $a = $b and $a= clone $b in PHP OOP
What is the difference between $a = &$b, $a = $b and $b = clone $a in PHP OOP? $a is an instance of a class.
Anonim Wd
- 65
- 2
- 9
2
votes
1 answer
Direct initialization != copy initialization when converting from different type?
I always thought direct initialization and copy initialization for types T that do not match the class type are absolutely equal. Yet I seem to be mistaken. The following code doesn't compile if I copy initialize (using = ) and only compiles when I…
glades
- 3,778
- 1
- 12
- 34
2
votes
1 answer
Is copy constructor still involved in copy initialization?
Consider the following code:
class Y {};
class X
{
public:
X() { }
X(const Y&) { }
explicit X(const X&) { }
};
X f()
{
return X();
}
int main()
{
Y y;
X x = y;
f();
}
The code gives an error (cannot convert from 'X' to…
CPPL
- 726
- 1
- 10
2
votes
1 answer
Implicit initialization by argument deduction for a templated class array
I have an item class, thats really a wrapper around an int.
I have a templated node class. I pass item class to it as template parameter.
I want to create an array of the templated node class, but compiler does not like it.
When I create a single…
bsobaid
- 955
- 1
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