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.
After posting one of my most controversial answers here, I dare to ask a few questions and eventually fill some gaps in my knowledge.
Why isn't an expression of the kind ((type_t *) x) considered a valid lvalue, assuming that x itself is a pointer…
I'm trying to do this in C++:
class Abc
{
int callFunction1()
};
void function1(Abc** c1) {//do something}
int Abc::callFunction1()
{
function1(&this);
return 0;
}
And I get "expression must be an l-value or function designator" error in…
When programming in C++03, we can't pass an unnamed temporary T() to a function void foo(T&);. The usual solution is to give the temporary a name, and then pass it like:
T v;
foo(v);
Now, along comes C++0x - and now with rvalue references, a…
$4.2/1 - "An lvalue or rvalue of type
“array ofN T” or “array of unknown
bound of T” can be converted to an
rvalue of type “pointer to T.” The
result is a pointer to the first
element of the array."
I am not sure how do we get an rvalue…
In "Lvalues and rvalues", [basic.lval] (3.10), the C++ standard contains a list of types such that it is valid to "access the stored value of an object" through a glvalue of such a type (paragraph 10). Specifically, it says:
If a program attempts…
I made a small 'blocking queue' class. It irritates me that I have created redundant code for values passed into the enqueue member function.
Here are the two functions that do the same exact thing (except the rvalue uses std::move to move the…
Example:
typedef enum Color
{
RED,
GREEN,
BLUE
} Color;
void func(unsigned int& num)
{
num++;
}
int main()
{
Color clr = RED;
func(clr);
return 0;
}
I get the following error when I compile this:
: In function…
In the C89 standard, I found the following section:
3.2.2.1 Lvalues and function designators
Except when it is the operand of the sizeof operator, the unary & operator, the ++ operator, the -- operator, or the left operand of the . operator or an…
I have the following code, which I cannot get to work:
struct foo {};
foo foo1 = {};
template
class FooClass {};
template
void foobar(FooClass arg) {
}
int main() {
FooClass f;
foobar(f);
}
The error…
In my code, I have something like this:
unordered_multimap > mEntities;
...
vector > rawEntities;
if (qi::phrase_parse(&buf[0], (&buf[0]) + buf.size(), EntityParser(),…
I am trying to understand C++11 rvalue references and how to use them for optimal performance in my code.
Let's say we have a class A that has a member pointer to a large amount of dynamically allocated data.
Furthermore, a method foo(const A& a)…
This is a followup from function template does not recognize lvalue
Lets play with the following code:
#include
template
void func(T&&) {
std::cout<<"in rvalue\n";
}
template
void func(const T&) {
std::cout<<"in…
For example,
int x[10];
int i = 0;
x = &i; //error occurs!
According to C - A Reference Manual, an array name cannot be an lvalue. Thus, x cannot be an lvalue. But, what is the reason the array name cannot be an lvalue? For example, why does an…
string foo() { return "hello"; }
int main()
{
//below should be illegal for binding a non-const (lvalue) reference to a rvalue
string& tem = foo();
//below should be the correct one as only const reference can be bind to…
So I wanted to practice the usage of std::forward and created a Test class with 2 constructors. 1 with T& and the other with T&& as overload. T& prints lvalue, and T&& prints rvalue so I know which one of the constructors is being used. I create 2…
