How do I use emplace vs push with std::multiset?

When working with a std::multiset in C++, you have the option to use either emplace or push methods to add elements. Understanding the difference between these two methods can help you write more efficient code.

The push method is used to insert a new element into the multiset. It requires an existing object to be created and passed to the multiset, which means the object is created prior to insertion.

On the other hand, the emplace method constructs an object in-place. This means that you can pass the arguments required to create the object, and emplace will construct it directly in the multiset, potentially leading to performance improvements by avoiding unnecessary copying or moves.

Here is an example that demonstrates the use of both methods:


    #include <iostream>
    #include <set>
    
    class MyClass {
    public:
        MyClass(int value) : value(value) {}
        int value;
        
        // Required for multiset to order objects correctly
        bool operator<(const MyClass &other) const {
            return value < other.value;
        }
    };

    int main() {
        std::multiset mySet;

        // Using push (requires an object to be created first)
        MyClass obj1(1);
        mySet.insert(obj1);

        // Using emplace (constructs the object in-place)
        mySet.emplace(2);

        // Output the values in the multiset
        for (const auto &item : mySet) {
            std::cout << item.value << " ";
        }
        return 0;
    }

C++ std::multiset emplace push performance insertion objects

How do I use emplace vs push with std::multiset?

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How do I use emplace vs push with std::multiset?

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