5 ms·

-3^5 = -(3^5) Not to defend that guy or anything.

by ryanf 16y ago

CamperBob 16y ago
Yeah, because it's impossible to be a skilled C programmer without knowing this stuff by heart. /rolls eyes
- ryanf 16y ago
  There are plenty of confusing order-of-operation things in C, especially around pointers, but is "&x + 1" really one of them? I basically know nothing about this subject and it's still pretty clear that the & would take precedence. Would you balk at that expression if x were an int pointer?
  - CamperBob 16y ago
    This particular case isn't that interesting because if the expression were equivalent to &(x+1) the compiler would complain about taking the address of a non-lvalue. But ryanf, while not defending "that guy" (me), made my point for me: if I have to stop and think about whether -3^5 == -(3^5) because some hotshot didn't consider it manly to use parentheses, nobody wins. If I were writing that expression I'd use (yes, completely unnecessary) parentheses around &a out of habit... the same habit that wouldn't let me write -3^5. Either way, it doesn't burn any more cycles.
    - deleted 16y ago
      [deleted]
  - Poiesis 16y ago
    I don't like guessing. "Yeah, I think it has high precedence" doesn't cut it any more than "Yeah, I think that is supposed to non-null" does. I try not to make assumptions. Does this mean I write code so that it can be read by someone with little experience? Yes, generally. Does this mean I am constantly having to verify my assumptions, as if I don't know anything? Yes, it does. There are some things that I'll take a pass on verifying, but if elevates a problem and everything else checks out, I'm going to seart looking at the parts that I "know" are fine.
- zwetan 16y ago
  no, but you will certainly never be a skilled C programmer if you don't reckonize a reference even me a noob in C I can see that it is indeed a reference (as I said I m a noob =))
pvg 16y ago
Unary - still has higher precedence in C (over the bitwise XOR operator). In case you mean exponentiation, these expressions would always be equal regardless of the precedence of the operators.
- lepton 16y ago
  (-3)^4 != -(3^4) when ^ means exponentiation.
  - pvg 16y ago
    It does for the expression given, silly. And again, in mathematical notation, unary - would take precedence over exponentiation so it's completely unclear what that person's example is supposed to mean and why it has upvotes.
    - ryanf 16y ago
      I was actually originally going to say -3 * 5 = -(3 * 5), as a joke. But from what I could find online, it looks like unary minus traditionally falls below exponentiation in the order of operations for math. See http://mathforum.org/library/drmath/view/53194.html http://mathforum.org/library/drmath/view/53194.html and Wikipedia: "In written or printed mathematics, the expression −3^2 is interpreted to mean −(3^2) = −9."
      - CamperBob 16y ago
        I think we have a QED here. :)
        ryanf 16y ago
        Obviously there are some cases where you should use parentheses. The reference operator just seems like a strange place to draw the line. I mean, to me it seems like the least confusing part of the quoted line.

-3^5 = -(3^5) Not to defend that guy or anything.

by ryanf 16y ago

-3^5 = -(3^5) Not to defend that guy or anything.

CamperBob 16y ago

Yeah, because it's impossible to be a skilled C programmer without knowing this stuff by heart. /rolls eyes

ryanf 16y ago
There are plenty of confusing order-of-operation things in C, especially around pointers, but is "&x + 1" really one of them? I basically know nothing about this subject and it's still pretty clear that the & would take precedence. Would you balk at that expression if x were an int pointer?
- CamperBob 16y ago
  This particular case isn't that interesting because if the expression were equivalent to &(x+1) the compiler would complain about taking the address of a non-lvalue. But ryanf, while not defending "that guy" (me), made my point for me: if I have to stop and think about whether -3^5 == -(3^5) because some hotshot didn't consider it manly to use parentheses, nobody wins. If I were writing that expression I'd use (yes, completely unnecessary) parentheses around &a out of habit... the same habit that wouldn't let me write -3^5. Either way, it doesn't burn any more cycles.
  - deleted 16y ago
    [deleted]
- Poiesis 16y ago
  I don't like guessing. "Yeah, I think it has high precedence" doesn't cut it any more than "Yeah, I think that is supposed to non-null" does. I try not to make assumptions. Does this mean I write code so that it can be read by someone with little experience? Yes, generally. Does this mean I am constantly having to verify my assumptions, as if I don't know anything? Yes, it does. There are some things that I'll take a pass on verifying, but if elevates a problem and everything else checks out, I'm going to seart looking at the parts that I "know" are fine.
zwetan 16y ago
no, but you will certainly never be a skilled C programmer if you don't reckonize a reference even me a noob in C I can see that it is indeed a reference (as I said I m a noob =))

pvg 16y ago

Unary - still has higher precedence in C (over the bitwise XOR operator). In case you mean exponentiation, these expressions would always be equal regardless of the precedence of the operators.

lepton 16y ago
(-3)^4 != -(3^4) when ^ means exponentiation.
- pvg 16y ago
  It does for the expression given, silly. And again, in mathematical notation, unary - would take precedence over exponentiation so it's completely unclear what that person's example is supposed to mean and why it has upvotes.
  - ryanf 16y ago
    I was actually originally going to say -3 * 5 = -(3 * 5), as a joke. But from what I could find online, it looks like unary minus traditionally falls below exponentiation in the order of operations for math. See http://mathforum.org/library/drmath/view/53194.html http://mathforum.org/library/drmath/view/53194.html and Wikipedia: "In written or printed mathematics, the expression −3^2 is interpreted to mean −(3^2) = −9."
    - CamperBob 16y ago
      I think we have a QED here. :)
      - ryanf 16y ago
        Obviously there are some cases where you should use parentheses. The reference operator just seems like a strange place to draw the line. I mean, to me it seems like the least confusing part of the quoted line.