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from what i've heard, c transforms expr1[expr2] in *(expr1+expr2), right?
but this is madness it means that you could, for example, say:
i++[x]; // where x is a array (pointer)
seems crazy to me. Is it correct?
2nd thought: if it IS correct, then how will you obsfucate multi dimenssional arrays? j[i++[x[k]][l] ??? how does the compiler know which is the column or the line?
this is really madness now...
Here's a good reference.
Quzah.
well, i found out that i++[x] is correct, but i'm still not clear about obfuscated examples. does any compiler has its rules?
also about obfuscated things, look at the following example:
*++b ? (*++b + *(b-1)) : 0
b-1 is calculated with b or with ++b ?
i'm just asking because i've come across some 'nice' code...
Why are you even bothering with this stuff?
1. Changing a[i] into i[a] has NO practical applications, so whilst it's a curiosity, it's not useful enough to worry about.
2. *++b ? (*++b + *(b-1)) : 0
Read the FAQ which Quzah posted (all of it).
Find out why all expressions with multiple side effects are undefined, no matter how 'nice' they are.
well, just asking... i'm not using them don't worry.
Isn't this statement okay?Quote:
Originally Posted by Salem
Isn't b only modified once in between sequence points?Code:*++b ? (*++b + *(b-1)) : 0
Which happens first, *++b or *(b-1)?Quote:
Originally Posted by pianorain
http://www.cppreference.com/operator_precedence.htmlQuote:
Originally Posted by Dave_Sinkula
Seems simple enough. (b-1) would be evaluated first.
>Seems simple enough. (b-1) would be evaluated first.
Or perhaps second. There's no guarantee.
I believe the order of evaluation for binary + is unspecified, so either one could happen before the other.
After playing with it and reading back through previous threads, I see that I was totally ignoring the following sentence: "Between the previous and next sequence point an object shall have its stored value modified at most once by the evaluation of an expression. Furthermore, the prior value shall be accessed only to determine the value to be stored." Makes sense now.