On 05/09/17 23:29, Grant Edwards wrote:
On 2017-09-05, Marko Rauhamaa<ma...@pacujo.net> wrote:
Pointer arithmetics is not an essential part of C. One could argue that
it was a mistake to include it in the language.
One may argue that it was a mistake, but I remember at least one
implementation where pointer arithmetic was hugely more efficient than
indexing into arrays. Incrementing a pointer through an array was
way, way faster than indexing through the array by incrementing an
array subscript.
But, that was 25 years ago on an 8-bit CPU where where integer
multiplies were expensive. The last time I compare the two methods
with a recent GCC on a 32-bit CPU, it generated pretty much the same
code either way...
That's the optimiser at work, turning what you wrote into the best fit
to the processor architecture. On an ARM, for example, that would
likely still be incrementing a pointer through an array.
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Rhodri James *-* Kynesim Ltd
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