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In C language, Why does n++ execute faster than n=n+1?
(int n=...; n++;)
(int n=...; n=n+1;)
Our instructor asked that question in today’s class. (this is not homework)
That would be true if you are working on a “stone-age” compiler…
In case of “stone-age”:
++nis faster thann++is faster thann=n+1Machine usually have
increment xas well asadd const to xn++, you will have 2 memory access only (read n, inc n, write n )n=n+1, you will have 3 memory access (read n, read const, add n and const, write n)But today’s compiler will automatically convert
n=n+1to++n, and it will do more than you may imagine!!Also on today’s out-of-order processors -despite the case of “stone-age” compiler- runtime may not be affected at all in many cases!!
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