Standard PHP Library (SPL) with Basic details

Question: What is full form of SPL?
Standard PHP Library.


Question: What is SPL?
It is collection of interfaces and Classes.


Question: Do we need to download library for SPL?
No, We need not to download external library.


Question: What does provide SPL?
SPL provides following Iterators, Interface and Functions.

1. Set of standard Data Structure.
2. a Iterators to traverse over objects
3. Set of Interfaces
4. Set of standard Exceptions
5. SPL Functions
6. SPL File Handling

Question: What classes are available in SPL data structure?
Doubly Linked Lists: It is a list of nodes linked in both directions to each other. Iterator operations, access to both end node, addition or removal of nodes.
http://php.net/manual/en/class.spldoublylinkedlist.php

Heaps: Heaps are tree-like structures that follow the General heap, each node is greater than or equal to its children.
http://php.net/manual/en/class.splheap.php

Arrays: Arrays are structures that store the data in a continuous way, accessible via indexes.
http://php.net/manual/en/class.splfixedarray.php

Map: A map is a datastructure holding key-value pairs. PHP arrays can be seen as maps from integers/strings to values.
http://php.net/manual/en/class.splobjectstorage.php



Question: What Iterators classes are available in SPL?

1. AppendIterator
2. ArrayIterator
3. CachingIterator
4. CallbackFilterIterator
5. DirectoryIterator
6. EmptyIterator
7. FilesystemIterator
8. FilterIterator
9. GlobIterator
10. InfiniteIterator
11. IteratorIterator
12. LimitIterator
13. MultipleIterator
14. NoRewindIterator
15. ParentIterator
16. RecursiveArrayIterator
17. RecursiveCachingIterator
18. RecursiveCallbackFilterIterator
19. RecursiveDirectoryIterator
20. RecursiveFilterIterator
21. RecursiveIteratorIterator
22. RecursiveRegexIterator
23. RecursiveTreeIterator
24. RegexIterator

Question: What Interfaces are available in SPL?

1. Countable
2. OuterIterator
3. RecursiveIterator
4. SeekableIterator
5. SplObserver
6. SplSubject

Question: What Exception classes are available in SPL?

1. BadFunctionCallException
2. BadMethodCallException
3. DomainException
4. InvalidArgumentException
5. LengthException
6. LogicException
7. OutOfBoundsException
8. OutOfRangeException
9. OverflowException
10. RangeException
11. RuntimeException
12. UnderflowException
13. UnexpectedValueException

Question: What are the advantage of iterators?

1. Laziness: the data is only fetched when you actually need it.
2. Reduced memory usage: SPL iterators encapsulate the list and expose visibility to one element at a time making them far more efficient.

Question: Give an example of Iterating Arrayst?

  
$arr = array("One", "Two", "three", "Four", "Five", "Six");
$iter = new ArrayIterator($arr);
foreach ($iter as $key => $value) {
    echo $key . ":  " . $value ;
}

Output

  
0: One
1: Two
2: three
3: Four
4: Five
5: Six

Question: Give an example of Iterating Directory Listings?

  
$dir = new DirectoryIterator("/");
foreach ($dir as $item) {
    echo $item . "
";
}

Output

  
$RECYCLE.BIN
Backup
banner
blog backup
data
data.log.txt
desktop files
doremon
mm
mongodb

Question: Give an example of Iterating Directory Recursively?

  
$iter = new RecursiveDirectoryIterator("/");
foreach (new RecursiveIteratorIterator($iter) as $item) {
    echo $item . "
";
}

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