data structures using c++1 chapter 13 standard template library (stl) ii

Data Structures Using C++ 1

Chapter 13

Standard Template Library (STL) II


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


Class pairThe 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


Relational Operators for the class pair


Type pair and Function make_pair

template<class T1, class T2>

pair<T1, T2> make_pair(const T1& X, const T2& Y)

{

return (pair<T1, T2>(X, Y));

}

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.


Associative Containers in STL• Elements in associative container automatically

sorted according to some ordering criteria• Default ordering criterion is relational operator <

(less than) • Users can also specify their own ordering criterion• Predefined Associative Containers

– Sets– Multisets– Maps– multimaps


Various Ways to Declare a Set/Multiset Container


Operations in a set or multiset


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 < (less than)

• User can also specify other sorting criteria• For user-defined data types, relational operators

must be properly overloaded



• 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



• 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 <map>


Various Ways to Declare a map/multimap Container


Operations in a map/multimap


Containers, Header Files, and Iterators


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


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


STL Algorithm Classification

• Numeric algorithms– Designed to perform numeric calculations on

elements

• Heap algorithms– Implement heap sort


Nonmodifying Algorithms


Modifying Algorithms


Numeric and Heap Algorithms


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


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

• STL’s function objects contained in header file functional


Arithmetic STL Function Objects


Relational STL Function Objects


Logical STL Function Objects


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


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


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


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 container’s insert operation in place of the

assignment operator


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



• remove: used to remove certain elements from a sequence

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



• 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



• 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


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


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


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


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


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


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


Chapter Summary

• Standard Template Library (STL)

• Associative Containers

• Operations on associative containers

• Function and algorithms on associative containers

• Example usage of function and algorithms

data structures using c++1 chapter 13 standard template library (stl) ii

Documents

data structures

class pair slide

multimap containers

container map

mapmultimap container

container multimap

setmultiset container

mapmultimap slide