How to detect the last iteration in a loop

kristoffer.carlsson · February 8, 2021, 10:17am

There is no way, in general, to know that an iteration is done until you actually get nothing back from iterate So you need to remember two values while iterating. This is how join does it:

github.com

JuliaLang/julia/blob/5ab3ed6415bacb2fd4dd41302bde010c46074c2f/base/strings/io.jl#L266-L281


      
          function join(io::IO, strings, delim, last)
              first = true
              local prev
              for str in strings
                  if @isdefined prev
                      first ? (first = false) : print(io, delim)
                      print(io, prev)
                  end
                  prev = str
              end
              if @isdefined prev
                  first || print(io, last)
                  print(io, prev)
              end
              nothing
          end

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How to detect the last iteration in a loop

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