API/Runtime/Core/Algo/Algo__RemoveIf

[giscus[bot]]

API/Runtime/Core/Algo/Algo__RemoveIf

Moves all elements which do not match the predicate to the front of the range, while leaving all other elements is a constructed but unspecified state.

https://docs.unrealengine.com/API/Runtime/Core/Algo/Algo__RemoveIf/

[soraphis]

Usage Example:

		TArray<int> foo{-3, -4, 7, 0, 2, 1, 3, 17, 200, -300};
		const auto StartIdx = Algo::RemoveIf(foo, [](const int Val)
		{
			return Val > 3;
		});

Results in:

    StartIdx = 7             vv
    foo = -3,-4,-300,0,2,1,3,17,200,-300

Corrections

The documentation states

Returns: The index of the first element after those which were not removed.

this is obviously wrong, it returns the first element after those which WERE removed, as the removed elements are in the front

Notes

The name, is a bit missleading, as the description states:

Moves all elements which do not match the predicate to the front of the range

A better name would be "KeepIf" / "Filter" / "Where" (if you come from C# LINQ)