Understanding more about i++ and i=i+1

Question

I was wondering if there is difference between the two forms of increment. Some of the links says i++ is faster that i=i+1;

Also as one of the person my observation is

Answer 1

Runthe code profiler between both of them it will be same for both i++ and i = i+1 for current version of gcc compiler. This purely depends on the compiler optimizations.

If you speak about processor specifically you can see the below chart for machine cycles,

INC - Increment

    Usage:  INC     dest
    Modifies flags: AF OF PF SF ZF

    Adds one to destination unsigned binary operand.

                             Clocks                 Size
    Operands         808x  286   386   486          Bytes

    reg8              3     2     2     1             2
    reg16             3     2     2     1             1
    reg32             3     2     2     1             1
    mem             15+EA   7     6     3            2-4  (W88=23+EA)

ADD - Arithmetic Addition

    Usage:  ADD     dest,src
    Modifies flags: AF CF OF PF SF ZF

    Adds "src" to "dest" and replacing the original contents of "dest".
    Both operands are binary.

                             Clocks                 Size
    Operands         808x  286   386   486          Bytes

    reg,reg           3     2     2     1             2
    mem,reg         16+EA   7     7     3            2-4  (W88=24+EA)
    reg,mem          9+EA   7     6     2            2-4  (W88=13+EA)
    reg,immed         4     3     2     1            3-4
    mem,immed       17+EA   7     7     3            3-6  (W88=23+EA)
    accum,immed       4     3     2     1            2-3

You can find the machine cycles taken for each instruction ADD and INC for various processors, 8086, 80286, 80386, 80486,above, you can find this documented in intel processor manuals. Lower the machine cycles faster the response.