c++ remove all elements equal to

To remove all elements equal to a specific value in C++, you can use the erase-remove idiom. The erase-remove idiom is a common technique used to efficiently remove elements from a container without leaving any gaps.

Here are the steps to remove all elements equal to a specific value in C++:

  1. Include the necessary header files: Make sure to include the <algorithm> header file to use the std::remove function, and the appropriate container header file (e.g., <vector>, <list>, etc.) for the container you are using.

  2. Define the container and initialize it: Declare and initialize your container with the elements you want to remove from.

  3. Use the std::remove function: Call the std::remove function, passing in the beginning and end iterators of your container, as well as the value you want to remove. This function moves all elements that are not equal to the specified value to the front of the container.

  4. Erase the removed elements: After calling std::remove, you need to erase the removed elements from the container. You can do this by calling the erase function on the container, passing in the iterator returned by std::remove as the starting point and the end iterator as the endpoint.

Here's an example that demonstrates how to remove all elements equal to a specific value from a vector:

#include <algorithm>
#include <vector>

int main() {
    std::vector<int> numbers = {1, 2, 3, 2, 4, 2, 5};

    int valueToRemove = 2;

    numbers.erase(std::remove(numbers.begin(), numbers.end(), valueToRemove), numbers.end());

    return 0;
}

In this example, we have a vector numbers with some elements. We want to remove all elements equal to the value 2. The std::remove function moves all the elements that are not equal to 2 to the front of the vector. Then, the erase function is called to remove the elements after the new end of the vector, effectively removing all occurrences of the value 2.

After executing this code, the numbers vector will only contain the elements that are not equal to 2. In this case, the resulting vector will be {1, 3, 4, 5}.

Remember to adjust the container type and value to remove based on your specific needs.