How Can I Efficiently Concatenate Vectors in Multithreaded Programming?

Concatenating Vectors for Multithreaded Data Merging

In multithreaded programming, there often arises a need to merge results from different threads. One common scenario is the concatenation of vectors. The task is to create a new vector that contains elements from two existing vectors.

One efficient approach to concatenate vectors involves preallocating memory to the destination vector and then using the insert() function to append elements from the source vectors. Here's the code snippet:

<code class="cpp">std::vector<int> A;
std::vector<int> B;
std::vector<int> AB;

AB.reserve( A.size() + B.size() ); // preallocate memory
AB.insert( AB.end(), A.begin(), A.end() );
AB.insert( AB.end(), B.begin(), B.end() );</code>

The reserve() function prepares the destination vector AB to hold A.size() B.size() elements. This optimization avoids unnecessary reallocations during the concatenation process.

The insert() function is called twice to append elements from both A and B to AB. It efficiently adds a range of elements into the AB vector while maintaining its order.

By utilizing this approach, you can efficiently concatenate vectors in multithreaded scenarios, ensuring the correct merging of results from different threads.

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