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What are containers in C++?
What are containers in C++?
A collection of objects defined with template classes.
Name the main types of containers in C++.
Name the main types of containers in C++.
List, vector, stack, queue, map.
Which operation would you use to insert an element in a vector?
Which operation would you use to insert an element in a vector?
Which method returns the number of elements in a vector?
Which method returns the number of elements in a vector?
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The first element of a vector is indexed by 1.
The first element of a vector is indexed by 1.
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What is the time complexity of accessing an element by index in a vector?
What is the time complexity of accessing an element by index in a vector?
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What is the purpose of the v.clear() method in a vector?
What is the purpose of the v.clear() method in a vector?
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In C++, a ______ allows automatic memory management.
In C++, a ______ allows automatic memory management.
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How is a new list initialized with a specific size in C++?
How is a new list initialized with a specific size in C++?
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Match the following container methods with their usage:
Match the following container methods with their usage:
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Study Notes
Introduction to STL Containers
- STL containers are collections of objects.
- Template classes define containers, separating the container from the data type inside.
- Each container type is optimized for specific uses (access/modification).
- Main containers include list, vector, stack, queue, and map.
Vector Operations
-
Insert:
v.push_back()adds an element. -
Remove:
v.pop_back()removes an element from the end. -
Clear:
v.clear()removes all elements. -
First Element:
v.begin()returns an iterator to the first element. -
Last Element:
v.end()returns an iterator to one position after the last element. -
Specific Element:
v[i]returns the element at position i (0-based index). -
Size:
v.size()returns the number of elements. -
Empty Check:
v.empty()returns true if the vector is empty.
Container Types
- List: Inserts and removes elements anywhere in constant time; uses automatic memory management.
- Vector: General purpose, fast access by index (constant time); removes elements from the end in constant time; other inserts and removes take linear time.
- Set/Map: Accesses elements by a key in constant time; provides fast search.
Container Constructors
- Example using
listandvector:-
list<int> one_list;creates an empty list. -
list<double> second_list(10, 4.22);creates a list of 10 doubles, all initialized to 4.22. -
list<double> third_list(second_list);creates a copy ofsecond_list. -
vector<string> one_vector;creates an empty vector of strings. -
vector<int> two_vector(4);creates a vector of 4 integers with undefined values.
-
Container Properties
- Containers have their own elements.
- Elements must support copy and assignment instructions.
- All containers have empty() and size() methods in constant time.
- All containers have begin() and end() methods.
Choosing a Container
- Consider the purpose of accessing elements (randomly, sequentially).
- Consider the needed modifications (add, delete, sort, etc.)
- Factors affecting performance include access time, modification time, number of elements, and memory usage. (e.g. linear, log, exponential time).
Iterators and their Purpose
- Iterators: Pointer generalization, used for sequential element access, and optimizing operations based on the container type.
- Iterator Definition: Identifies a container and an element; lets you examine the stored value; provides operations between elements; restricts operations to those handled efficiently by the type of container.
Using Iterators
- In the example code using iterators, looping through vector elements
- Iterators for containers are used to loop and access the elements of a container
Standard Library Algorithms
- STL algorithms are functions designed for use with containers, requiring iterators/pointers for element access; they do not affect container structure.
- for_each, find, copy, replace, rotate, set_union, and min_elements are example functions.
Associative Containers
- Needed when finding a value in a sequential container quickly.
- Advantage: arrange elements and exploit order to locate quicker.
- They are stored in a particular order based on the key value
Associative Array (map)
- The key is associated with a value.
- Keys don't need to be integers, any comparable values can be used.
- Keys must be unique.
- Containers are self-ordering: the program shouldn't change the element order.
Map Operations
- Operations include begin(), end(), empty(), and size(); operator[] to access elements; insert and erase methods affect elements; and find, lower_bound, and upper_bound for iterators and returning specified values.
Using Associative Functions
- Examples use maps for counting word occurrences in a sentence or for decomposing a list of names into groups based on first letters.
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Description
This quiz covers the basics of Standard Template Library (STL) containers in C++. It explores different types of containers like lists, vectors, stacks, queues, and maps, discussing their unique operations and advantages. Test your understanding of how these containers function and their specific use cases.
