What is the difference between `std::remove` and `std::erase` in C and how are they used together?

Understanding the Distinction Between Erase and Remove

Introduction:
In the realm of C programming, the std::remove and std::erase algorithms are often encountered when manipulating containers. While both are used for modifying elements, their operations differ in crucial ways.

Functionality of std::remove:
std::remove reorders elements within a container by shifting non-removed elements forward to fill the spaces left by removed elements. It doesn't actually delete elements; instead, it designates them as "removed" and marks their positions within the container.

Non-deletion Behavior of std::remove:
The reason for this non-deletion behavior lies in the design of std::remove. It's designed to work with arbitrary forward iterator pairs, which may not have the ability to delete elements. For instance, it can be used with pointers to C arrays, which cannot be resized.

Understanding std::size() After std::remove:
Even after applying std::remove, the std::size() function still returns the original container size. This is because the removed elements are still present in the container, albeit marked as such. To reduce the container's size and remove the designated elements, you must use std::erase after std::remove.

Example with erase-remove Idiom:
The "erase-remove" idiom combines std::remove and std::erase to efficiently remove elements from a container. By first using std::remove to isolate the elements to be removed, you can then erase them using std::erase, which updates the container's size accordingly.

Conclusion:
Understanding the difference between std::remove and std::erase is crucial for effectively manipulating containers in C . By correctly using both algorithms together, you can ensure that elements are removed from containers and that their sizes are updated accordingly.

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