Inequality operator

General Usage
1

Why is there the difference between != and !== operators?

Examples:

julia> a = Any["D", "A", "s", "t"]
julia> filter(e->e!="s",a)
3-element Array{Any,1}:
 "D"
 "A"
 "t"
julia> filter(e->e !== "s",a)
4-element Array{Any,1}:
 "D"
 "A"
 "s"
 "t"
2

see the docs for ===

!== is the negation of === and != the negation of ==

What version of Julia are you using ?

in julia 1.6:

julia> a = Any["D", "A", "s", "t"]
4-element Vector{Any}:
 "D"
 "A"
 "s"
 "t"

julia> filter(e->e != "s",a)
3-element Vector{Any}:
 "D"
 "A"
 "t"

julia> filter(e->e !== "s",a)
3-element Vector{Any}:
 "D"
 "A"
 "t"
1 Like
3

Cheers!

LTS, of course :stuck_out_tongue:

(I’m smiling, because a while ago, I was told here, that it’s better not to stick to LTS)

4

This is for sure a weird bug

julia> versioninfo()
Julia Version 1.0.5
Commit 3af96bcefc (2019-09-09 19:06 UTC)
Platform Info:
  OS: Windows (x86_64-w64-mingw32)
  CPU: Intel(R) Core(TM) i7-9750H CPU @ 2.60GHz
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-6.0.0 (ORCJIT, skylake)

julia> a = ["D", "A", "s", "t"];

julia> filter(e->e !== "s", a)
3-element Array{String,1}:
 "D"
 "A"
 "t"

julia> filter(e->e !== "s", Any[a;])
4-element Array{Any,1}:
 "D"
 "A"
 "s"
 "t"

the compiler (?) probably thinks that since they are not the same type, they can’t be ===

5

I get the same results as you do. The example above was taken from SO post related to filter.

Julia Version 1.0.5
Commit 3af96bcefc (2019-09-09 19:06 UTC)
Platform Info:
  OS: Linux (x86_64-pc-linux-gnu)
  CPU: Intel(R) Core(TM) i7-10750H CPU @ 2.60GHz
  WORD_SIZE: 64
  LIBM: libopenlibm
  LLVM: libLLVM-6.0.0 (ORCJIT, skylake)

But in my code I had a string array, so it should have been working. But I didn’t use a string constant, but a string parsed from the symbol.

julia> a = ["D", "A", "s", "t"];
julia> ss = :s;
julia> filter(e->e !== string(ss),a)
4-element Array{String,1}:
 "D"
 "A"
 "s"
 "t"
julia> filter(e->e != string(ss),a)
3-element Array{String,1}:
 "D"
 "A"
 "t"