L-value represents the address of the value. "L" stands for the left side, because the address it is what is required when the variable appears on the left side of an assignment operation.
For some reason I didn't manage to find this exact question. Why is it allowed to bind an rvalue to const lvalue reference, although it is impossible to to the same without the const?
I do understand that the lifetime of the rvalue gets an extension…
Given types A,B, I am concerned with the exact definition of std::common_type, disregarding the variadic case std::common_type for arbitrary types A.... So let
using T = decltype(true ? std::declval() : std::declval());
using C =…
I'm having trouble printing a member of a struct that is returned from a function:
#include
struct hex_string
{
char a[9];
};
struct hex_string to_hex_string_(unsigned x)
{
static const char hex_digits[] = "0123456789ABCDEF";
…
I know there are topics that are similar to this one already (such as this).
The example given in this topic was this:
std::string & rs1 = std::string();
Clearly, that std::string() is an rvalue. However, my question is why is s1 legal while s2 is…
This is a follow-on question to
C++0x rvalue references and temporaries
In the previous question, I asked how this code should work:
void f(const std::string &); //less efficient
void f(std::string &&); //more efficient
void g(const char * arg)
{
…
What i think is that dynamic type means dynamically allocated object using new. In the following case, do you say p points to dynamic type or static type of object? In standard, it doesn't say about dynamic type being dynamic object.
1.3.3 - The…
This is a bit of an inverse of all the "lvalue required as left operand of assignment" error questions.
I have a class that overloads operator[], but only the version that returns a temporary. If it were to return an int:
struct Foo
{
int…
It is stated here that
The term modifiable lvalue is used to emphasize that the lvalue allows the designated object to be changed as well as examined. The following object types are lvalues, but not modifiable lvalues:
An array type
An incomplete…
Let's consider the following code:
int main() {
int i = 2;
int b = ++i++;
return 3;
}
It compiles with the following with an error:
: In function 'int main()':
:3:16: error: lvalue required as increment operand
3 |…
An lvalue is a value bound to a definitive region of memory whereas an rvalue is an expression value whose existence is temporary and who does not necessarily refer to a definitive region of memory. Whenever an lvalue is used in a position in which…
I tried to understand lvalue and rvalue in C++11. So I wrote a test code:
int x = 10;
int foo() { return x; }
int& bar() { return x; }
int&& baz() { return 10; }
int main() {
int& lr1 = 10; // error: lvalue references rvalue
int& lr2 =…
I know that the code written below is illegal
void doSomething(std::string *s){}
int main()
{
doSomething(&std::string("Hello World"));
return 0;
}
The reason is that we are not allowed to take the address of a temporary object. But my…
I try to define a class A as follows:
template< typename T >
class A
{
public:
A( T elem )
: _elem( elem )
{}
private:
TYPE _elem; // "TYPE" should be either "T" in case "elem" is an r-value or "T&" in case "elem" is an…
const and volatile are called cv-qualifier by the C spec.
What is exactly defference between specifier and qualifier (cv-qualifier)? Is a qualifier is a specifier as well?
Is it necessarry that qualifier is with an lvalue only?
What are qualifiers…
