Both emplace_back
and push_back
are methods used to add an element to the end of a C++ vector. However, there are some differences:
push_back
takes an existing object while emplace_back
constructs the object in placeThe push_back
method copies an existing object into the vector, while emplace_back
constructs the new object in place, using its constructor arguments. For example, if Person
is a class with a constructor that requires a name and age:
vector<Person> people;
people.emplace_back("Alice", 25); // constructs a new Person object directly in the vector
Person p("Bob", 30);
people.push_back(p); // copies an existing Person object into the vector
emplace_back
can be more efficientemplace_back
can be more efficient than push_back
when dealing with complex objects. This is because it avoids creating a temporary object that needs to be copied into the vector. Instead, it constructs the new object directly in the vector's memory.
emplace_back
is more flexibleSince emplace_back
constructs the object in place, it can be used to add elements of a variety of types (as long as they have a constructor that can be called with the given arguments). push_back
, on the other hand, requires an object of the vector's type to be passed in.
In summary, emplace_back
is a more efficient and flexible way to add elements to a C++ vector, especially for complex types. However, push_back
is still useful when dealing with simple types or when you already have an existing object that you want to add to the vector.
Asked: 2023-03-31 11:00:00 +0000
Seen: 10 times
Last updated: May 14 '21