C++ Iterator

🚶‍♂️ C++ Iterator – Move Through Containers Like a Pro

An iterator in C++ is like a smart pointer that walks through elements of a container (like a vector or list) one by one.

It helps you loop over containers without knowing their structure. Imagine a robot with a map who knows where to go next!

📦 Why Use Iterators?

• They work with all STL containers (like vector, list, etc.)
• They are more flexible than plain loops
• You can move them forward, backward, and even modify data

🔧 Example: Iterating Over a Vector

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

int main() {
    vector<int> nums = {10, 20, 30};

    vector<int>::iterator it;
    for (it = nums.begin(); it != nums.end(); ++it) {
        cout << *it << " ";
    }

    return 0;
}
  

🎯 Shortcut with auto Keyword

C++11 introduced auto to make code shorter and easier to read.

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

int main() {
    vector<int> nums = {5, 10, 15};

    for (auto it = nums.begin(); it != nums.end(); ++it) {
        cout << *it << " ";
    }

    return 0;
}
  

💡 Tip: Common Iterator Functions

• begin() – points to the first element
• end() – points just after the last element
• *it – gives you the value at iterator
• ++it – moves to the next item

✅ Summary

• Iterators help you loop through containers easily
• Use begin() and end() to define your loop
• auto makes the code clean and readable