24 Ranges library [ranges]

24.7 Range adaptors [range.adaptors]

24.7.5 Transform view [range.transform]

24.7.5.1 Overview [range.transform.overview]

1
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transform_­view presents a view of an underlying sequence after applying a transformation function to each element.
2
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The name views​::​transform denotes a range adaptor object ([range.adaptor.object]).
Given subexpressions E and F, the expression views​::​transform(E, F) is expression-equivalent to transform_­view{E, F}.
3
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[Example
: 
vector<int> is{ 0, 1, 2, 3, 4 };
transform_view squares{is, [](int i) { return i * i; }};
for (int i : squares)
  cout << i << ' '; // prints: 0 1 4 9 16
— end example
]