C++ Vector

📦 C++ Vector – Stretchy Array with Superpowers

A vector in C++ is like an array that can grow and shrink as needed. It’s part of the STL (Standard Template Library), and it makes life way easier than old-school arrays.

Think of a vector as a flexible container that expands when you add more stuff. 🎒

📌 Include Vector Header

#include <vector>

🛠️ Declaring a Vector

vector<int> nums;         // Empty vector of integers
vector<string> names(3);  // Vector of 3 strings
vector<int> odds = {1, 3, 5};  // Initialized vector

🧪 Example: Add and Print Values

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

int main() {
    vector<int> nums;

    nums.push_back(10);
    nums.push_back(20);
    nums.push_back(30);

    for (int n : nums) {
        cout << n << " ";
    }

    return 0;
}
  

✨ Common Vector Functions

• push_back(x) – Add an element to the end
• pop_back() – Remove the last element
• size() – Get number of elements
• at(i) – Access element at index i (with bounds checking)
• clear() – Remove all elements

🧠 Example: Using size() and at()

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

int main() {
    vector<string> fruits = {"Apple", "Mango", "Banana"};

    cout << "Total: " << fruits.size() << endl;
    cout << "First: " << fruits.at(0) << endl;

    return 0;
}
  

✅ Summary

• Vectors are dynamic arrays that grow and shrink.
• They’re part of the STL and super easy to use.
• Use functions like push_back, pop_back, at(), and size().