How to Implement Custom Iterators and Const_Iterators in C ?

Custom Iterators and Const_Iterators: Implementation Guide

When working with custom container classes, it becomes necessary to implement iterators and const_iterators to allow traversal and manipulation of elements. For those new to iterator creation, this guide provides essential guidelines and tips to ensure proper implementation.

Iterator Class Design:

1. Select the Suitable Iterator Type: Determine the type of iterator appropriate for your container. Options include input, output, forward, etc., based on the intended access patterns.
2. Leverage Base Iterator Classes: Utilize base iterator classes from the standard library, such as std::iterator with a specified iterator_category tag (e.g., random_access_iterator_tag). These classes provide essential type definitions and other functionality.

Avoiding Code Duplication:

To minimize code redundancy between const_iterator and iterator classes, consider:

1. Template-Based Design: Define the iterator class as a template, parameterizing it with "value type," "pointer type," and "reference type." This allows you to create both non-const and const iterators with distinct type definitions.

Example:

template <typename PointerType> class MyIterator {
    // Iterator class definition
};

typedef MyIterator<int*> iterator_type;
typedef MyIterator<const int*> const_iterator_type;

Additional Resources:

• Standard Library Reference: https://www.cplusplus.com/reference/iterator/iterator/

Note:

Since C 17, std::iterator has been deprecated. Refer to the linked discussion for more information.

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