On Tue, Apr 5, 2016 at 10:45 AM, Didier Verna <did...@didierverna.net> wrote: > > Hello, > > the manual says: "In Julia, exceeding the maximum representable value of > a given type results in a wraparound behavior:", but that seems to be > the case only for the native type and above: > > julia> typeof(typemax(Int64) + 1) -> Int64 > julia> typeof(typemax(Int128) + 1) -> Int128 > > but: > > julia> typeof(typemax(Int8) + 1) -> Int64 > julia> typeof(typemax(Int16) + 1) -> Int64 > julia> typeof(typemax(Int32) + 1) -> Int64 > > These last 3 results seem inconsistent (and the manual incorrect) > because for example, typeof(typemax(Int8)) -> Int8 and not Int64, so no, > Julia doesn't do modular arithmetics all the time.
The literal `1` has type `Int`. The promotion rules for `Int8` and `Int` state that, before the addition, `Int8` is converted to `Int`. (On your system, it seems that `Int` is `Int64`.) You can avoid this by writing `Int8(1)` instead of `1`; this should recover the wrap-around behaviour. Note that this wrap-around exists only for some simple operations (+ - * abs); e.g. for division, there is an error instead. -erik -- Erik Schnetter <schnet...@gmail.com> http://www.perimeterinstitute.ca/personal/eschnetter/
