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Template std.algorithm.comparison.equal

Compares two ranges for equality, as defined by predicate pred (which is == by default).

template equal(alias pred) ;

Contained Functions

NameDescription
equal Compares two ranges for equality. The ranges may have different element types, as long as pred(r1.front, r2.front) evaluates to bool. Performs Ο(min(r1.length, r2.length)) evaluations of pred.

Example

import std.algorithm.comparison : equal;
import std.math : approxEqual;

int[] a = [ 1, 2, 4, 3 ];
assert(!equal(a, a[1..$]));
assert(equal(a, a));
assert(equal!((a, b) => a == b)(a, a));

// different types
double[] b = [ 1.0, 2, 4, 3];
assert(!equal(a, b[1..$]));
assert(equal(a, b));

// predicated: ensure that two vectors are approximately equal
double[] c = [ 1.005, 2, 4, 3];
assert(equal!approxEqual(b, c));

Example

Tip

equal can itself be used as a predicate to other functions. This can be very useful when the element type of a range is itself a range. In particular, equal can be its own predicate, allowing range of range (of range...) comparisons. 

import std.algorithm.comparison : equal;
import std.range : iota, chunks;
assert(equal!(equal!equal)(
    [[[0, 1], [2, 3]], [[4, 5], [6, 7]]],
    iota(0, 8).chunks(2).chunks(2)
));

Authors

Andrei Alexandrescu

License

Boost License 1.0.