November 25, 2019
Amitraj
Containers:-
Containers are objects that hold data. The STL defines Ten containers which are grouped into three categories.
1. Sequence Containers
Sequence containers store elements in a linear sequence, like a line as shown in fig. each element is related to other elements by its position along the line. They all expand themselves to allow insertion of elements and all of them support a number of operations on them.
The STL provides 3 types of sequence containers:
1. Vector
2. list
3. deque
-> Elements in all these containers can be accessed using an iterator. The difference between the 3 of them is related to only their performance.
2. Associative Containers
These containers are designed to support direct access to elements using keys. They are not sequential. There are four types of associative containers:
1. Set
2. Multiset
3. Map
4. Multimap
-> All these containers store data in a structure called tree which facillitates fast searching, deletion, and insertion. However, these are very slow for random access and inefficient for sorting.
-> Containers set and multiset can store a number of items and provide operations for manipulating them using the values as the keys.
-> Containers map and multimap are used to store pairs of items, one called the key and the other called the value. The main difference between map and multimap is that a map allows only one key for a given value to be stored while multimap permits multiple keys.
3. Derived Containers
The STL provides three derived containers namely; stack, queue, priority_queue. These are also known as container adaptors.
-> stack , queues and priority_queues can be created from different sequence containers. The derived containers do not support iterators and therefore we can not use them for data manipulation. However , they support two member functions pop() and push() for implementing, deleting and inserting operations.
Containers supported by STL
Applications of Containers classes
1. Container classes make programmers more productive.
2. Container classes let programmers write more robust code.
3. The vector is the most widely used container. it stores element in continguous memory locations and enables direct access using subscript operator []. A vector can change its size dynamically and therefore allocates memory as needed at run time.
4. Lists supports bidirectional, linear list and provides an efficient implementation for deletion and insertion operations. unlike a vector, which supports random access, A list can be accessed sequentially only.
5. Map is a sequence of (key,value) pairs where a single value is associated with each unique key. A map is a commonly called an associative array. The key is specified using the subscript operator[].
Containers are objects that hold data. The STL defines Ten containers which are grouped into three categories.
1. Sequence Containers
Sequence containers store elements in a linear sequence, like a line as shown in fig. each element is related to other elements by its position along the line. They all expand themselves to allow insertion of elements and all of them support a number of operations on them.
The STL provides 3 types of sequence containers:
1. Vector
2. list
3. deque
-> Elements in all these containers can be accessed using an iterator. The difference between the 3 of them is related to only their performance.
2. Associative Containers
These containers are designed to support direct access to elements using keys. They are not sequential. There are four types of associative containers:
1. Set
2. Multiset
3. Map
4. Multimap
-> All these containers store data in a structure called tree which facillitates fast searching, deletion, and insertion. However, these are very slow for random access and inefficient for sorting.
-> Containers set and multiset can store a number of items and provide operations for manipulating them using the values as the keys.
-> Containers map and multimap are used to store pairs of items, one called the key and the other called the value. The main difference between map and multimap is that a map allows only one key for a given value to be stored while multimap permits multiple keys.
3. Derived Containers
The STL provides three derived containers namely; stack, queue, priority_queue. These are also known as container adaptors.
-> stack , queues and priority_queues can be created from different sequence containers. The derived containers do not support iterators and therefore we can not use them for data manipulation. However , they support two member functions pop() and push() for implementing, deleting and inserting operations.
Containers supported by STL
Containers
|
Description
|
Header file
|
Iterator
|
Vector
|
It can be defined as a dynamic array. It permits direct access to any element.
|
<vector>
|
Random access
|
List
|
It is a bidirectional linear list. It allows insertion and deletion anywhere
|
<list>
|
Bidirectional
|
deque
|
It is a double-ended queue. Allows insertions and deletions at both the ends. Permits direct access to any element.
|
<deque>
|
Random access
|
set
|
It is an associate container for storing unique sets. Allows rapid lookup.
|
<set>
|
Bidirectional
|
multiset
|
It is an associate container for storing non-unique sets.
|
<set>
|
Bidirectional
|
map
|
It is an associate container for storing unique key/value pairs. Each key is associated with only one value.
|
<map>
|
Bidirectional
|
multimap
|
It is an associate container for storing key/value in which one key may be associated with more than one value (one-to-many mapping). It allows a key-based lookup.
|
<map>
|
Bidirectional
|
stack
|
A standard stack follows last-in-first-out(LIFO)
|
<stack>
|
No iterator
|
queue
|
A standard queue follows first-in-first-out(FIFO)
|
<queue>
|
No iterator
|
priority-queue
|
The first element out is always the highest priority element
|
<queue>
|
No iterator
|
Applications of Containers classes
1. Container classes make programmers more productive.
2. Container classes let programmers write more robust code.
3. The vector is the most widely used container. it stores element in continguous memory locations and enables direct access using subscript operator []. A vector can change its size dynamically and therefore allocates memory as needed at run time.
4. Lists supports bidirectional, linear list and provides an efficient implementation for deletion and insertion operations. unlike a vector, which supports random access, A list can be accessed sequentially only.
5. Map is a sequence of (key,value) pairs where a single value is associated with each unique key. A map is a commonly called an associative array. The key is specified using the subscript operator[].
