Write-only range algorithms
We began this chapter looking at algorithms such as std::find that march through a range reading its elements in order without modification. You might be surprised to learn that the inverse operation also makes sense: there is a family of standard algorithms that march through a range modifying each element without reading it!
std::fill(a,b,v) does what its name implies: fill each element of the given range [a,b) with a copy of the provided value v.
std::iota(a,b,v) is slightly more interesting: it fills the elements of the given range with copies of ++v. That is, std::iota(a,b,42) will set a[0] equal to 42, a[1] equal to 43, a[2] equal to 44, and so on all the way up to b. This algorithm's funny name comes from the APL programming language, where a function named ι (that's the Greek letter iota) performed this operation. Another funny thing about this algorithm is that, for whatever reason, its definition is found in the standard <numeric> header instead...
