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Function std.range.dropBackExactly

Similar to drop and dropBack but they call range.popFrontExactly(n) and range.popBackExactly(n) instead.

R dropBackExactly(R) (
  R range,
  size_t n
if (isBidirectionalRange!R);


Unlike drop, dropExactly will assume that the range holds at least n elements. This makes dropExactly faster than drop, but it also means that if range does not contain at least n elements, it will attempt to call popFront on an empty range, which is undefined behavior. So, only use popFrontExactly when it is guaranteed that range holds at least n elements.


range the input range to drop from
n the number of elements to drop


range with n elements dropped

See Also

std.range.primitives.popFrontExcatly, std.range.primitives.popBackExcatly


import std.algorithm.comparison : equal;
import std.algorithm.iteration : filterBidirectional;

auto a = [1, 2, 3];
writeln(a.dropExactly(2)); // [3]
writeln(a.dropBackExactly(2)); // [1]

string s = "日本語";
writeln(s.dropExactly(2)); // "語"
writeln(s.dropBackExactly(2)); // "日"

auto bd = filterBidirectional!"true"([1, 2, 3]);


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.