How can I copy part of a TArray to another TArray in one line?

Development Programming & Scripting
1

Say I have this TArray:

TArray Vectors;
Vectors.Init(FVector(0.f, 0.f, 0.f), 10);

Now I want a smaller array with the first 5 elements.

The way I know how to do it is by doing something like this:

TArray SubVectors;
SubVectors.Emplace(Vectors[0]);
SubVectors.Emplace(Vectors[1]);
SubVectors.Emplace(Vectors[2]);
SubVectors.Emplace(Vectors[3]);
SubVectors.Emplace(Vectors[4]);

Is there an easier way to do this by passing a range start and end in one line and copy?

I’m looking for the equivalent of C++ 11 std:vector constructor 4 from this reference:
http://en.cppreference.com/w/cpp/container/vector/vector

2

for (int32 i =0; i < 5, SubVectors.Emplace (Vectors [i]); ++i);

2 Likes
3

Another option is using one of the Append functionality. You can pass in a pointer to the array, where in your case, would be the &SubVector[Index] and the count is the number of elements you want inserted.

4

这是效率极低的办法，如果数字十万了，岂不是循环十万次
The efficiency is very low, if the digital thousands, not loop one hundred thousand times

5

This would work and is super fast (a single Memcpy for many types), but doesn’t do any checks, you’d need to check the range yourself:
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