this post was submitted on 19 Jun 2023
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I gave it a shot in Compiler Explorer, with the following code:
GCC takes the
i-=-1
and optimizes it intoADD DWARD PTR [rbp-4], 1
, and changing it around to++i
ori++
makes no difference.So, at least in C and C++, it works all the same. Even on unsigned integers.
It works the same because the value of the last expression in the
for
loop is not used for anything. It's the side effect of that statement that counts. Eg, the value ofi
is checked the next time the for loop is executed by the condition check. Try replacingi
in the condition check instead withi++
or++i
and you would see different results.Something like:
for (int i = 0; ++i < 10;) { ... }