Standard Template Library STL II

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Chapter 13

• Standard Template Library (STL) II

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Chapter Objectives

• Learn more about the standard template library
  (STL)
• Become familiar with the associative containers
• Explore how associative containers are used to
  manipulate data in a program
• Learn about various generic algorithms

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Class pair

• The class pair has two constructors the default
  constructor,
• and a constructor with two parameters. The
  general syntax to
• declare an object of the type pair is

• where expr1 is of the type Type1 and expr2 is of
  the
• type Type2

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Relational Operators for the class pair
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Type pair and Function make_pair
The header file utility also contains the
definition of the function template
make_pair. With the help of the function
make_pair, we can create pairs without
explicitly specifying the type pair.
templateltclass T1, class T2gt pairltT1, T2gt
make_pair(const T1 X, const T2 Y) return
(pairltT1, T2gt(X, Y))
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Associative Containers in STL

• Elements in associative container automatically
  sorted according to some ordering criteria
• Default ordering criterion is relational operator
  lt (less than)
• Users can also specify their own ordering
  criterion
• Predefined Associative Containers
• Sets
• Multisets
• Maps
• multimaps

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Various Ways to Declare a Set/Multiset Container
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Various Ways to Declare a Set/Multiset Container
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Operations in a set or multiset
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Associative Containers map and multimap

• Containers map and multimap manage their elements
  in the form key/value
• Elements automatically sorted according to some
  sort criteria applied on key
• Default sorting criterion is relational operator
  lt (less than)
• User can also specify other sorting criteria
• For user-defined data types, relational operators
  must be properly overloaded

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Associative Containers map and multimap

• Only difference between containers map and
  multimap is container multimap allows
  duplicates, whereas the container map does not
• The name of the class defining the container map
  is map the name of the class defining the
  container multimap is multimap

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Associative Containers map and multimap

• The name of the header file containing the
  definitions of the classes map and multimap, and
  the definitions of the functions to implement
  various operations on these containers, is map
• Therefore, to use any of these containers, the
  program must include the following statement
• include ltmapgt

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Various Ways to Declare a map/multimap Container
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Various Ways to Declare a map/multimap Container
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Operations in a map/multimap
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Containers, Header Files, and Iterators
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Algorithms

• Some operations very specific to container
  provided as part of container definition
• Generic algorithms common to all containers
  contained in header file algorithm
• Find
• Sort
• Merge

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STL Algorithm Classification

• Nonmodifying algorithms
• Investigate, do not modify elements of container
• Modifying algorithms
• Modify the elements of a container by
  rearranging, removing, or changing the values of
  the elements
• Mutating algorithms change order f elements but
  not their value

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STL Algorithm Classification

• Numeric algorithms
• Designed to perform numeric calculations on
  elements
• Heap algorithms
• Implement heap sort

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Nonmodifying Algorithms
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Modifying Algorithms
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Numeric and Heap Algorithms
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Function Objects

• To make the generic algorithms flexible, the STL
  usually provides two forms of an algorithm using
  the mechanism of function overloading
• First form of algorithm uses natural operation to
  accomplish this goal
• In second form, user can specify criteria based
  on which the algorithm processes the elements

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Function Objects

• A function object contains a function that can be
  treated as a function using the function call
  operator, ()
• A function object is a class template that
  overloads the function call operator, ()
• In addition to allowing you to create your own
  function objects, STL provides arithmetic,
  relational, and logical function objects
• STLs function objects contained in header file
  functional

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Arithmetic STL Function Objects
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Relational STL Function Objects
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Relational STL Function Objects
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Logical STL Function Objects
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Predicates

• Special types of function objects that return
  boolean values
• Unary predicates check a specific property for a
  single argument
• Binary predicates check a specific property for a
  pair of (two) arguments

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Predicates

• Typically used to specify a searching or sorting
  criterion
• In STL, always return the same result for the
  same value
• The functions that modify their internal states
  cannot be considered predicates

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Insert Iterators

• STL provides three insert iterators to insert
  elements at destination
• Class vector does not support the push_front
  operation, this iterator cannot be used for a
  vector container

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Insert Iterators

• Back_inserter
• Uses the push_back operation of the container in
  place of the assignment operator
• Front_inserter
• Uses the push_front operation of the container in
  place of the assignment operator
• Inserter
• Uses the containers insert operation in place of
  the assignment operator

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Functions and Their Uses

• fill used to fill a container with elements
• fill_n used to fill in the next n elements
• generate and generate_n used to generate
  elements and fill a sequence
• find, find_if, find_end, and find_first_of used
  to find the elements in a given range

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Functions and Their Uses

• remove used to remove certain elements from a
  sequence
• remove_if used to remove certain elements from a
  sequence using some criterion

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Functions and Their Uses

• remove_copy copies the elements in a sequence
  into another sequence by excluding certain
  elements from the first sequence
• remove_copy_if copies the elements in a sequence
  into another sequence by excluding certain
  elements, using some criterion, from the first
  sequence

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Functions and Their Uses

• swap, iter_swap, and swap_ranges used to swap
  elements
• search, search_n, sort, and binary_search used
  to search elements
• adjacent_find used to find the first occurrence
  of consecutive elements satisfying a certain
  criterion

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Algorithms

• merge merges two sorted lists
• inplace_merge used to combine two sorted,
  consecutive sequences
• reverse reverses the order of the elements in a
  given range
• reverse_copy reverses the order of the elements
  in a given range while copying into a destination
  range.The source is not modified

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Algorithms

• rotate rotates the elements in a given range
• rotate_copy copies the elements of the source at
  the destination in a rotated order
• count counts the occurrences of a specified
  value in a given range
• count_if counts the occurrences of a specified
  value in a given range satisfying a certain
  criterion

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Algorithms

• max used to determine the maximum of two values
• max_element is used to determine the largest
  element in a given range
• min used to determine the minimum of two values
• min_element used to determine the smallest
  element in a given range

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Algorithms

• random_shuffle used to randomly order the
  elements in a given range
• for_each used to access and process each element
  in a given range by applying a function, which is
  passed as a parameter
• transform creates a sequence of elements by
  applying certain operations to each element in a
  given range

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Algorithms

• includes determines whether the elements of one
  range appear in another range
• set_intersection used to find the elements that
  are common to two ranges of elements
• set_union used to find the elements that are
  contained in two ranges of elements
• set_difference used to find the elements in one
  range of elements that do not appear in another
  range of elements

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Algorithms

• set_symmetric_difference given two ranges of
  elements, determines elements in first range but
  not the second, or in second range but not first
• accumulate, adjacent_difference, inner_product,
  and partial_sum numerical functions that
  manipulate numeric data

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Chapter Summary

• Standard Template Library (STL)
• Associative Containers
• Operations on associative containers
• Function and algorithms on associative containers
• Example usage of function and algorithms