C++/STL Algorithms

< C++

The STL contains functions for common algorithms within C++.

find

Finds a value within a range.

Example:

#include <set>
#include <algorithm>

using namespace std;

int main()
{
set<int> TestContainer;
''// Add some elements here''
TestContainer.insert(1);
TestContainer.insert(5);
TestContainer.insert(3);
TestContainer.insert(11);
''// Find the 3 in the container''
set<int>::iterator MyIterator = find(TestContainer.begin(),TestContainer.end(),3);
if(MyIterator != TestContainer.end())
cout<<*MyIterator;
else
cout<< "Error: 3 is not in the container" << endl;
}

copy

Copies a range of elements.

copy_backward reverses the order of elements.

swap

Swaps two sets.

#include <iostream>
#include <algorithm>
#include <set>

using namespace std;

int main()
{

set <char> sCreatedSet1 = { '1', '2', '7', '4', '5', '6', '3', '8', '9' };
set <char> sCreatedSet2 = { 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i' };
set<char>::iterator iter1 = sCreatedSet1.begin();
set<char>::iterator iter2 = sCreatedSet2.begin();

cout << "-Set elements before swap-" << endl;
for (auto y : sCreatedSet1)
{
cout << *iter1 << '\t' << *iter2 << endl;
iter1++;
iter2++;
}

swap(sCreatedSet1, sCreatedSet2);
iter1 = sCreatedSet1.begin();
iter2 = sCreatedSet2.begin();

cout << "-Set elements after swap-" << endl;
for (auto y : sCreatedSet1)
{
cout << *iter1 << '\t' << *iter2 << endl;
iter1++;
iter2++;
}
return 0;
}

iter_swap

Swaps two elements pointed to by iterators.

transform

Applies a function to a range.

random_shuffle

Randomly shuffles a range.

sort

Sorts elements in a range.

A stable_sort retains the original order of equal elements. A stable_sort does not provide any advantage over a simple sort of, say, a list of integer values (if the list contains multiple values of "2", it doesn't matter which "2" comes first). However, consider the example of sorting a list of Employee objects by their first name only. Two different employees may share the same first name (which gives them the ordering relative to the rest of the list). If "Bob Smith" was before to "Bob Jones" in the list prior to the sort, then stable_sort would guarantee Smith was before Jones in the sorted list; sort does not make such a guarantee. The stable_sort algorithm is marginally less efficient due to added constraint.

binary_search

Searches a sorted range for a value.

next_permutation

Transforms a range to the next permutation.

Reversed by prev_permutation.