120 lines
3.5 KiB
Org Mode
120 lines
3.5 KiB
Org Mode
* What is a C++ iterator :cpp:iterator:concept:recognition:
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:PROPERTIES:
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:ANKI_NOTE_TYPE: Basic
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:ANKI_NOTE_ID: 1776621491263
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:END:
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** Front
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What is an iterator in C++?
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** Back
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An object that points to elements in a container and allows traversal through them, providing a common interface for accessing elements sequentially without exposing the underlying structure.
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* Task: Traverse a vector with iterators :cpp:iterator:production:code:
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:PROPERTIES:
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:ANKI_NOTE_TYPE: Basic
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:ANKI_NOTE_ID: 1776621491259
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:END:
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** Front
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Write C++ code to iterate through a std::vector<int> using iterators
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** Back
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#+begin_src c++
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std::vector<int> vec = {1, 2, 3};
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for (auto it = vec.begin(); it != vec.end(); ++it) {
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std::cout << *it << " ";
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}
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#+end_src
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* Iterator operations :cpp:iterator:concept:enumeration:
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:PROPERTIES:
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:ANKI_NOTE_TYPE: Basic
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:ANKI_NOTE_ID: 1776621491255
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:END:
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** Front
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What are the four required operations for a C++ iterator?
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** Back
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- `operator*` — dereference to get current element
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- `operator++` — advance to next element (pre and post)
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- `operator==` — equality comparison
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- `operator!=` — inequality comparison
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* cpp iterator categories :cpp:iterator:concept:enumeration:
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:PROPERTIES:
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:ANKI_NOTE_TYPE: Basic
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:ANKI_NOTE_ID: 1776621491250
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:END:
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** Front
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List the five iterator categories in C++ (from simplest to most advanced)
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** Back
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:PROPERTIES:
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:ANKI_NOTE_ID: 1777826854918
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:END:
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1. Input Iterator — read values, advance once
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2. Output Iterator — write values, advance once
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3. Forward Iterator — read/write, multiple passes
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4. Bidirectional Iterator — + operator--
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5. Random Access Iterator — + arithmetic, subscript
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* Task: Use const iterator :cpp:iterator:production:code:
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:PROPERTIES:
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:ANKI_NOTE_TYPE: Basic
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:ANKI_NOTE_ID: 1776621491246
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:END:
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** Front
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Write C++ code to safely traverse a const std::vector without modifying elements
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** Back
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#+begin_src c++
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std::vector<int> vec = {1, 2, 3};
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for (auto it = vec.cbegin(); it != vec.cend(); ++it) {
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std::cout << *it << " ";
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}
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#+end_src
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* Task: Use reverse iterator :cpp:iterator:production:code:
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:PROPERTIES:
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:ANKI_NOTE_TYPE: Basic
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:ANKI_NOTE_ID: 1776621491241
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:END:
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** Front
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Write C++ code to iterate backwards through a std::vector
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** Back
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#+begin_src c++
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std::vector<int> vec = {1, 2, 3};
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for (auto it = vec.rbegin(); it != vec.rend(); ++it) {
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std::cout << *it << " ";
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}
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#+end_src
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* Minimal custom iterator implementation :cpp:iterator:implementation:production:
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:PROPERTIES:
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:ANKI_NOTE_TYPE: Basic
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:ANKI_NOTE_ID: 1776621491237
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:END:
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** Front
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Write the minimal C++ code to implement a forward iterator for a custom class
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** Back
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#+begin_src c++
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class MyIterator {
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Node* ptr;
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public:
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reference operator*() const { return ptr->data; }
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pointer operator->() const { return &ptr->data; }
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MyIterator& operator++() { ptr = ptr->next; return *this; }
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MyIterator operator++(int) { auto tmp = *this; ++*this; return tmp; }
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bool operator==(const MyIterator& other) const { return ptr == other.ptr; }
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bool operator!=(const MyIterator& other) const { return !(*this == other); }
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};
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#+end_src
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* When to use iterators vs indices :cpp:iterator:concept:comparison:
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:PROPERTIES:
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:ANKI_NOTE_TYPE: Basic
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:ANKI_NOTE_ID: 1776621491226
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:END:
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** Front
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When would you choose iterators over index-based loops in C++?
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** Back
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- Container type is unknown or could change (iterators abstract the container)
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- Using standard library algorithms (std::find, std::sort, etc.)
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- Need to traverse multiple containers simultaneously
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- Working with containers without random access (list, map)
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- Decouple algorithm from container structure
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