Suppose I have a class with private memebers ptr, name, pname, rname, crname and age. What happens if I don't initialize them myself? Here is an example:
class Example {
private:
int *ptr;
string name;
string *pname;
…
For example, I cannot write this:
class A
{
vector v(12, 1);
};
I can only write this:
class A
{
vector v1{ 12, 1 };
vector v2 = vector(12, 1);
};
Why is there a difference between these two declaration syntaxes?
Please explain how to use member initializer lists.
I have a class declared in a .h file and a .cpp file like this:
class Example
{
private:
int m_top;
const int m_size;
/* ... */
public:
Example(int size, int grow_by = 1) :…
Consider the following code in which we initialize part of D based on another part of D:
struct c {
c() : D{rand(), D[0]} {}
int D[2];
};
int main() {
c C;
assert(C.D[0] == C.D[1]);
}
Is the above program well-defined? Can we…
class A {
int x;
static int i;
};
int x = 10;
int A::i = x;
When I compile the code above, it get the error
:8:12: error: invalid use of non-static data member 'A::x'
8 | int A::i = x;
| ^
:2:9: note:…
I run across a weird concept named "member initializer".
Here says:
C++11 added member initializers, expressions to be applied to members
at class scope if a constructor did not initialize the member itself.
What is its definition?
Are there…
I'm sure this is a really simple question. The following code shows what I'm trying to do:
class MemberClass {
public:
MemberClass(int abc){ }
};
class MyClass {
public:
MemberClass m_class;
MyClass(int xyz) {
if(xyz == 42)
…
Brace-or-equal-initializers in an anonymous struct within a struct doesn't do their work on output produced by VS2013. There's the code:
#include
#include
struct S
{
struct
{
uint64_t val = 0;
…
I agree with the consensus that it's generally best to initialise C++ data members in a member initialization list rather than the body of a constructor, but I am sceptical of this explanation
The other (inefficient) way to build constructors is…
I have a member of class A in my own class which constructor takes multiple parameters. Im forwarding parameters of my own class to the constructor of class A. But its important that these parameters are correct, so i need to check them before…
While (re)implementing a simple constexpr map, I wrote this
(godbolt):
template
class flat_map
{
private:
struct pair
{
key_type key;
value_type value;
};
const pair…
During the member initialisation of a class with multiple members, it seems desirable to be able to catch an exception generated by any specific member initialiser, to wrap in additional context for rethrowing, but the syntax of a function-try-block…
Consider the code:
#include
#include
struct stru {
int a{};
int b{};
};
int main() {
std::atomic as;
auto s = as.load();
std::cout << s.a << ' ' << s.b << std::endl;
}
Note that although stru has default member…
For example, I have two classes
class Foo;
class Bar;
class Foo {
const Bar &m_bar;
...
};
class Bar {
const Foo &m_foo;
...
};
Let foo is object of Foo and bar is object of Bar. Is there any way (normal or "hacking") to create/initialize…
