Copying Algorithms

Ensuring Destination Space when Copying

What happens if the destination container does not have enough space to accommodate all copied elements?

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If the destination container does not have enough space to accommodate all the elements being copied, the behavior is undefined, and it may lead to a crash or other unpredictable behavior.

Therefore, it’s crucial to ensure that the destination container has sufficient space before performing the copy operation.

Here’s how you can ensure that the destination container has enough space:

  1. Resize the Destination Container: Use the resize() method to adjust the size of the destination container.
  2. Check Size in Advance: Compare the sizes of the source and destination containers before copying.

Here’s an example demonstrating both methods:

#include <algorithm>
#include <iostream>
#include <vector>

int main() {
  std::vector<int> Source{1, 2, 3};
  std::vector<int> Destination(6);  

  std::ranges::copy(Source, Destination.begin());

  for (int Value : Destination) {
    std::cout << Value << ", ";
  }
}
1, 2, 3, 0, 0, 0,

In this example, the destination container is initialized with enough space (6 elements) to hold all copied elements.

Alternatively, you can dynamically resize the container if its current size is insufficient:

#include <algorithm>
#include <iostream>
#include <vector>

int main() {
  std::vector<int> Source{1, 2, 3};
  std::vector<int> Destination{0, 0};

  if (Destination.size() < Source.size()) {
    Destination.resize(Source.size()); 
  }

  std::ranges::copy(Source, Destination.begin());

  for (int Value : Destination) {
    std::cout << Value << ", ";
  }
}
1, 2, 3,

By resizing the destination container, you ensure it has enough space to hold all elements from the source container.

Remember, failing to ensure enough space can lead to undefined behavior, so always check and adjust the size of your destination container as needed.

Answers to questions are automatically generated and may not have been reviewed.

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