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Function std.range.retro

Iterates a bidirectional range backwards. The original range can be accessed by using the source property. Applying retro twice to the same range yields the original range.

auto retro(Range) (
  Range r
if (isBidirectionalRange!(Unqual!Range));


r the bidirectional range to iterate backwards


A bidirectional range with length if r also provides a length. Or, if r is a random access range, then the return value will be random access as well.

See Also

reverse for mutating the source range directly.


import std.algorithm.comparison : equal;
int[5] a = [ 1, 2, 3, 4, 5 ];
int[5] b = [ 5, 4, 3, 2, 1 ];
assert(equal(retro(a[]), b[]));
assert(retro(a[]).source is a[]);
assert(retro(retro(a[])) is a[]);


Andrei Alexandrescu, David Simcha, Jonathan M Davis, and Jack Stouffer. Credit for some of the ideas in building this module goes to Leonardo Maffi.


Boost License 1.0.