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.
Questions tagged [lvalue]
661 questions
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difference between rvalue reference and lvalue reference as argument
After reading the post:http://www.cprogramming.com/c++11/rvalue-references-and-move-semantics-in-c++11.html.
I can not figure out that when you write functions that take lvalue or rvalue references as arguments, such as this:
void printReference…
sydridgm
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Reference initialization in C++
Can anybody explain to me why there is a difference between these two statements?
class A{};
const A& a = A(); // correct
A& b = A(); // wrong
It says
invalid initialization of non-const reference of type A& from a…
skydoor
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Javascript Ternary Operator lvalue
I was reading about the ternary operator in different languages, and noticed something interesting in the Javascript section. http://en.wikipedia.org/wiki/%3F:#JavaScript
The conditional operator in JavaScript has the same syntax and precedence…
Ryan Dignard
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How is assignments to compound literals useful?
I was reading about compound literals, and I saw that they are l-values. So I suspected that you can assign them, so I did an experiment and I noticed that this compiles without warnings with gcc -Wall -Wextra -pedantic:
struct foo {
int x;
…
klutt
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lvalue required as increment operand error
#include
int main()
{
int i = 10;
printf("%d\n", ++(-i)); // <-- Error Here
}
What is wrong with ++(-i)? Please clarify.
Wei
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9
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3 answers
Check if a subroutine is being used as an lvalue or an rvalue in Perl
I'm writing some code where I am using a subroutine as both an lvalue and an rvalue to read and write database values. The problem is, I want it to react differently based on whether it is being used as an lvalue or an rvalue.
I want the subroutine…
tjwrona1992
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Where in the C++ Standard does it say ::delete can change lvalues?
I ran into my first compiler that changes the lvalue passed to ::delete, but doesn't zero out the lvalue. That is the following is true:
Foo * p = new Foo();
Foo * q = p;
assert(p != 0);
assert(p == q);
::delete p;
assert(p != q);
assert(p !=…
Ants
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error: invalid initialization of non-const reference of type ‘bool&’ from an rvalue of type ‘std::vector::reference {aka std::_Bit_reference}’
Why do I get the error: invalid initialization of non-const reference of type ‘bool&’ from an rvalue of type ‘std::vector::reference {aka std::_Bit_reference}’?
vector> vis;
bool& visited(int x, int y)
{
return vis[x][y];…
Mariusz Trela
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why does --list.end() compile?
list's end() returns a copy of the past-the-end iterator, right?
Therefore, list.end() is an rvalue, right?
the -- operator-function overloaded for list iterator takes a non-const reference, right?
you can't bind rvalues to non-const references,…
Armen Tsirunyan
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Why are multiple increments/decrements valid in C++ but not in C?
test.(c/cpp)
#include
int main(int argc, char** argv)
{
int a = 0, b = 0;
printf("a = %d, b = %d\n", a, b);
b = (++a)--;
printf("a = %d, b = %d\n", a, b);
return 0;
}
If I save the above as a .cpp file, it compiles and outputs…
mkosler
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c++: function lvalue or rvalue
I just started learning about rvalue references in c++11 by reading this page, but I got stuck into the very first page. Here is the code I took from that page.
int& foo();
foo() = 42; // ok, foo() is an lvalue
int* p1 = &foo(); // ok, foo()…
aminfar
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Binding temporary to a lvalue reference
I have the following code
string three()
{
return "three";
}
void mutate(string& ref)
{
}
int main()
{
mutate(three());
return 0;
}
You can see I am passing three() to mutate method. This code compiles well. My understanding is,…
Navaneeth K N
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When should I choose copy elision over passing argument by const reference?
Possible Duplicate:
Is pass-by-value a reasonable default in C++11?
I'm reading Want Speed? Pass by Value. by Dave Abrahams about copy elision and RVO. And I'm wondering why do we need the copy elision?
I have been told too many times that you…
amazingjxq
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Is a pointer an lvalue or rvalue?
In other post, I came across
(5.2.9/8) An rvalue of type "pointer to member of D of type cv1 T" can
be converted to an rvalue of type "pointer to member of B of type cv2
T", where B is a base class (clause 10) of D,
Note this from language…
user1086635
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