On Tue, 04 Jan 2011 08:55:07 -0500, spir <[email protected]> wrote:
Hello,
I'm bluffed by the 2 terms "l-value" & "r-value" used in C-line language
common terminologies. I think I guess what they mean, but I don't
understand the need for such absconse idioms. Why not:
l-value <-> variable
r-value <-> value (or expression)
?
I guess (*p) is considered an l-value. Indeed, it's a special way of
denoting a variable, matching the special case of a pointer. If correct,
this requires slightly extending the notion of variable (and/or of
identifier).
On the r-value side, I cannot find anything that makes it a distinct
concept from the one of value, or of expression.
Explanations welcome, thank you,
Denis
lvalue stands for left value, rvalue stands for right value. They
describe which side of the equation they are on:
lvalue = rvalue;
Why these terms instead of something more natural? Well, I have no idea
:) If I were to guess, it would be that no natural term could exactly
describe the meaning, and also that using natural terms are subjective.
There's no mistaking what lvalue and rvalue mean becausey they are defined
by the language itself.
I'm sure Walter probably knows the origin, l and r values are really
compiler terms, and he's been writing compilers for a long time.
-Steve
