Sometimes, implementation details do make a difference. Even with today's advanced optimizing compilers. And in the embedded systems world, where US$ 0.50 processors rule, the best available compilers often do not have the most advanced optimizers.

Example (in C):

i = count;
j = 0;
do {
    // something with j
    j++;
} while (--i);

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is often faster than the common: for (j = 0; j < count; j++) { } or even: for (i = count, j = 0; i; --i, j++) { }

This is because it's easy for an optimizer to "see" it can safely "replace" while (--i) with a decrement-and-branch-if-not-zero instruction.

(Also, if your code functions equally correctly with a decrementing "index", you can skip the extra variable and associated increment.)

In reply to Re^2: quickness is not so obvious by RonW
in thread quickness is not so obvious by DanBev

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