lvalue?

[Shraddha]

Sometimes we get an error of lvalue requred?What exactly is the lvalue?
And when this error occures?

 

[Walter Roberson]

Sometimes we get an error of lvalue requred?What exactly is the lvalue?
And when this error occures?

What did you come up with when you googled for lvalue ?

 

[Ben Pfaff]

Sometimes we get an error of lvalue requred?What exactly is the lvalue?

Informally speaking, an lvalue is an expression that can appear
on the left side of an assignment operator. Generally, an lvalue
is an expression that designates an object (a region of memory):
a variable, a dereferenced pointer, etc. In fact in C the
definition of an lvalue is different from what this informal idea
would suggest, but this is a reasonable place to start thinking
about them.

 

[Chris Dollin]

Informally speaking, an lvalue is an expression that can appear
on the left side of an assignment operator. Generally, an lvalue
is an expression that designates an object (a region of memory):
a variable, a dereferenced pointer, etc. In fact in C the
definition of an lvalue is different from what this informal idea
would suggest, but this is a reasonable place to start thinking
about them.

And there's plenty of stuff in the archives on this topic,
some of it more off-topic (but historically interesting)
than others.

[You get an "lvalue required" message when you are supposed
to have an lvalue but you didn't supply one; a typical
example would be assigning to an array or something++.]

 

[Tor Rustad]

Sometimes we get an error of lvalue requred?What exactly is the lvalue?
And when this error occures?

This is a FAQ, check Question 20.39b.

Let say i is a int, then consider the assignment

i = i + 1;

here the r.h.s "i" is an int value, while the identifier "i" on the l.h.s.
refers to something very different, namely a memory location.

Hence, l-value is the value of "i" on the l.h.s of the assignment, while
r-value refer to the value of the identifier on the r.h.s.