Can you give me some examples of using std::vector in C++17?

Can you give me some examples of using std::vector in C++17?

Sure! In C++17, std::vector is a dynamic array that can resize itself. Here's a simple example:

#include <iostream>
#include <vector>

int main() {
    std::vector<int> numbers = {1, 2, 3, 4, 5};
    numbers.push_back(6);
    for (int num : numbers) {
        std::cout << num << " ";
    }
    return 0;
}

This code initializes a vector with five integers and adds a sixth one.

What are some new features of std::vector in C++17?

C++17 introduced several features for std::vector, including:

1. std::vector::data() now returns a pointer to the underlying array.
2. Improved performance with std::vector::reserve() and std::vector::shrink_to_fit().
3. The ability to use std::optional with vectors for better handling of empty states.

Can you show me how to use std::vector with custom objects?

Absolutely! Here's an example of using std::vector with a custom class:

#include <iostream>
#include <vector>

class Person {
public:
    std::string name;
    Person(std::string n) : name(n) {}
};

int main() {
    std::vector<Person> people;
    people.emplace_back("Alice");
    people.emplace_back("Bob");
    for (const auto& person : people) {
        std::cout << person.name << " ";
    }
    return 0;
}

This code creates a vector of Person objects and prints their names.

What are the performance considerations when using std::vector?

When using std::vector, consider the following performance aspects:

1. Memory Allocation: Vectors allocate memory in chunks, which can lead to overhead if frequently resized.
2. Cache Locality: Vectors provide good cache locality, making them faster for iteration compared to linked lists.
3. Insertion/Deletion: Inserting or deleting elements in the middle of a vector can be costly, as it requires shifting elements.