C / C++ / MFC

George_George wrote:

You know, lvalue have modifiable and un-modifiable versions.

George_George wrote:

Do you agree

"in C++, string literals are l-values." in thread http://www.velocityreviews.com/forums/t279868-what-is-lvalue.html[^]? Why?

"abc" = "123";

"myohmy" = 17;

#include <string>

int main()
{
	"abc" = "123";

	"myohmy" = 17;

	return 0;
}

1>d:\visual studio 2008\projects\test_string2\test_string2\main.cpp(5) : error C2106: '=' : left operand must be l-value
1>d:\visual studio 2008\projects\test_string2\test_string2\main.cpp(7) : error C2440: '=' : cannot convert from 'int' to 'const char [7]'

George_George wrote:

Are you sure it can compile?

George_George wrote:

1. You agree string literal is rvalue?

manish.patel wrote:

t says that if we write x = 10; then x will be l-value(left side value)

In c++, we can not give number as variable name, It always be a string only.

So in C++, string literals are l-values.

George_George wrote:

What do you think of whether string literal is lvalue or rvalue? I think it is only rvalue, do you agree?

* ( ( char * ) & var ) = "str"[2]; // * ((char *)&var) too

int & varref = var;

varref = 1["str"]; // varref is also an lvalue

George_George wrote:

in post #2, what do the following statements mean? Especially the additional [2] after "str" and ["str"] after 1? Any ideas?

George_George wrote:

* ( ( char * ) & var ) = "str"[2]; // * ((char *)&var) too

const char * const szText = "str"; or const char szText[] = {"str"};
* ( ( char * ) & var ) = szText[2];

George_George wrote:

varref = 1["str"]; // varref is also an lvalue

struct C
{
C& operator=(int);
};

C() = 5; // OK to assign to r-value C();