Grant Edwards wrote: > On 2009-01-30, MRAB <goo...@mrabarnett.plus.com> wrote: > >>> What is the minimum amount of extra memory required to exchange two >>> 32-bit quantities? What would be the pseudocode that achieves this >>> minimum? >> x ^= y >> y ^= x >> x ^= y >> >> This is really only of use when working in assembly language. > > And rarely then. ;) > > [Readability counts everywhere.] > It can be useful if you want to swap the contents of 2 registers in ARM assembly language:
EOR r0,r0,r1 EOR r1,r0,r1 EOR r0,r0,r1 The quickest alternative is to use MOV: MOV r2,r0 MOV r0,r1 MOV r1,r2 The same number of instructions, program bytes, and clock cycles, but requiring an additional register! -- http://mail.python.org/mailman/listinfo/python-list
