learn-julia-the-hard-way
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chrisvoncsefalvay
Chapter 5: Strings
In the interpolation section, you talk about * and $ constructs, and mention that $ is faster than *, but you don't mention that string(...) is fastest of all.
Where a search string is not found, search() will yield 0:-1. That is an odd result, until you realise the reason: for any string s, s[0:-1] will necessarily yield "" (that is, an empty string).
Why is this the case? [1:-1] does the same thing, but [0:0] returns a BoundsError.
s[0,0] means 'give me all characters from the 0th to the 0th. Julia is 1-indexed, so you're asking for a non-existent index, and that's what Julia is trying to get at by the BoundsError.
OK, but that doesn't explain why [0:-1] works. It's "give me all the characters from the 0th to the -1st", which seems even more wrong than [0:0].
Ah, this explains it:
julia> [0:0]
1-element Array{Int64,1}:
0
julia> [0:-1]
0-element Array{Int64,1}
julia>