Iterators in C++

Operations of the iterator

Also see, Literals in C.Fibonacci Series in C++

Types of iterators

There are mainly five types of iterators:

Iterator Adaptors

Example of Iterators

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

int main() {
    vector<int> numbers = {10, 20, 30, 40, 50};
    vector<int>::iterator it;

    cout << "Elements of the vector: ";
    for (it = numbers.begin(); it != numbers.end(); ++it) {
        cout << *it << " ";
    }
    return 0;
}

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Explanation:

• A vector of integers is created with initial values.
• An iterator (it) is declared to traverse the vector.
• The begin() method initializes the iterator to the start of the vector, while the end() marks its termination.
• The loop prints each element by dereferencing the iterator using *it.

Iterator Utility Functions in C++

• std::advance: Moves an iterator forward by a specified number of steps.
• std::distance: Calculates the number of elements between two iterators.
• std::next: Returns an iterator advanced by a given number of positions.
• std::prev: Returns an iterator decremented by a given number of positions.
• std::inserter: Allows inserting elements into a container at a specific position.

Applications of Iterators with Examples

1. Accessing Container Elements

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

int main() {
    list<int> numbers = {1, 2, 3, 4, 5};
    for (auto it = numbers.begin(); it != numbers.end(); ++it) {
        cout << *it << " ";
    }
    return 0;
}

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Explanation: Iterators are used to traverse the list and print each element.

2. Reversing a Container

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

int main() {
    vector<int> numbers = {1, 2, 3, 4, 5};
    reverse(numbers.begin(), numbers.end());

    for (int num : numbers) {
        cout << num << " ";
    }
    return 0;
}

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Explanation: The reverse function uses iterators to modify the order of elements in the vector.

3. Inserting Elements at Specific Positions

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

int main() {
    vector<int> numbers = {1, 2, 3};
    auto it = numbers.begin();
    advance(it, 1); // Move iterator to the second position

    numbers.insert(it, 10);

    for (int num : numbers) {
        cout << num << " ";
    }
    return 0;
}

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Explanation: The advance function moves the iterator to the desired position, and the insert function places the new element there.

Advantages of Iterators

Following are the advantages of an iterator:

• Code Reusability: For the reusability of code, we use iterators. However, we first use iterators to access the list element elements.
• Ease in programming: It is better to use iterators rather than utilizing a subscript operator[] to access the elements of a container. If we use subscript operator[] to access the elements, we need to keep track of the number of elements added at the runtime, but this would not happen in the case of an iterator.
• Dynamic Processing: C++ iterators provide the facility to dynamically add or delete the data.

Disadvantages of Iterators

Following are the disadvantages of an iterator:

• Iterators won't work in the simultaneous movement of data structure from one to another.
• If we're going to update the structure being iterated, an iterator won't allow us to do so because of how it stores the position.
• The iterator will not work if we backtrack while processing through a list

We will close the article now with faqs since you get the overall idea of iterators.

Frequently Asked Questions

What is the advantage of the storage memory hierarchy architecture?

A Hierarchical Memory System – or Memory Hierarchy for short – is an economical solution to provide computer programs with (virtually) unlimited fast memory, taking advantage of the locality and cost-performance of memory technology.

Which is a more critical, processor or RAM?

RAM is the core of any computer or smartphone, and in most cases, more is always better. RAM is as important as the processor. The exact amount of RAM on your smartphone or computer enhances the performance and supports various types of software.

What will happen if RAM is not available in a computer system?

RAM is not available on the computer; it will not run or start. If you mean when it runs out of available RAM, the computer gets slow, and no paging is being used or virtual RAM, your computer will lock up and stop running.

What is the main difference between memory and CPU?

CPU is the Central Processing Unit, and it performs calculations (or, more precisely, computations). At the same time, memory is the temporary data storage space used by active processes being executed by the CPU.

How is RAM being used in computer architecture?

Because of its speed, RAM is used to process information immediately. When you want to accomplish a specific task, computer operating systems load data from the hard disk into RAM to process it, such as sort a spreadsheet or display it on screen.

Conclusion

This article taught us about the Iterators, the operators in iterators, and their types. And at the end of the blog, we also learned the pros and cons of iterators. To read more about the STL in C++, Visit Here.

Recommended Readings:

• Memory Hierarchy
• Java List Iterator

We hope that this blog has helped you enhance your knowledge regarding Methods in C# and if you would like to learn more, check out our articles in the code360 library. Do upvote our blog to help other ninjas grow. Happy Coding!