C++ Vectors

C++ Vectors: Dynamic Arrays

In standard C++, an array has a fixed size. Once you declare an array of size 5, it cannot hold a 6th element. This limitation is solved by Vectors.

A vector in C++ is a dynamic array provided by the STL. It can automatically resize itself whenever elements are added or removed.

1. Using Vectors

To use a vector, you must include the <vector> library at the top of your program.

Syntax:

#include <vector>

// vector<DataType> vectorName;
vector<int> numbers;

2. Adding and Removing Elements

Vectors are incredibly flexible. You can easily add elements to the end of a vector using .push_back(), and remove the last element using .pop_back().

#include <iostream>
#include <vector>
using namespace std;

int main() {
  // Create an empty vector of strings
  vector<string> cars;
  // Add elements
  cars.push_back("Volvo");
  cars.push_back("BMW");
  cars.push_back("Ford");
  // Access the first element
  cout << "First car: " << cars.front() << "\n";
  // Remove the last element ("Ford")
  cars.pop_back();
  // Check the current size
  cout << "Total cars now: " << cars.size() << "\n";
  return 0;
}

3. Why Use Vectors over Standard Arrays?

1. Dynamic Size: You don't need to know the size of the array at compile time.
2. Built-in Functions: Vectors come with incredibly useful methods like .size(), .empty(), .clear(), and more.
3. Memory Management: The vector handles its own memory dynamically behind the scenes, preventing many memory-leak issues that plague manual C++ arrays.