Cpp - STL algorithm－KwCheng's blog

In addition to container classes and iterators,

STL also provides a number of generic algorithms for working with the elements of the container classes.

These allow you to do things like search, sort, insert, reorder, remove, and copy elements of the container class.

To use any of the STL algorithms, simply include the algorithm header file.

min_element and max_element

The min_element and max_element algorithms find the min and max element in a container class:

#include <iostream>
#include <list>
#include <algorithm>
int main()
{
    using namespace std;
 
    list<int> li;
    for (int nCount=0; nCount < 6; nCount++)
        li.push_back(nCount);
 
    list<int>::const_iterator it; // declare an iterator
    it = min_element(li.begin(), li.end());
        cout << *it << " ";
    it = max_element(li.begin(), li.end());
        cout << *it << " ";
 
    cout << endl;
}

Prints:

0 5

find (and list::insert)

In this example, we’ll use the find() algorithm to find a value in the list class, and then use the list::insert() function to add a new value into the list at that point.

#include <iostream>
#include <list>
#include <algorithm>
int main()
{
    using namespace std;
 
    list<int> li;
    for (int nCount=0; nCount < 6; nCount++)
        li.push_back(nCount);
 
    list<int>::const_iterator it; // declare an iterator
    it = find(li.begin(), li.end(), 3); // find the value 3 in the list
    li.insert(it, 8); // use list::insert to insert the value 8 before it
 
    for (it = li.begin(); it != li.end(); it++) // for loop with iterators
        cout << *it << " ";
 
    cout << endl;
}

This prints the value

0 1 2 8 3 4 5

sort and reverse

In this example, we’ll sort a vector and then reverse it.

#include <iostream>
#include <vector>
#include <algorithm>
int main()
{
    using namespace std;
 
    vector<int> vect;
    vect.push_back(7);
    vect.push_back(-3);
    vect.push_back(6);
    vect.push_back(2);
    vect.push_back(-5);
    vect.push_back(0);
    vect.push_back(4);
 
    sort(vect.begin(), vect.end()); // sort the list
 
    vector<int>::const_iterator it; // declare an iterator
    for (it = vect.begin(); it != vect.end(); it++) // for loop with iterators
        cout << *it << " ";
 
    cout << endl;
 
    reverse(vect.begin(), vect.end()); // reverse the list
 
    for (it = vect.begin(); it != vect.end(); it++) // for loop with iterators
        cout << *it << " ";
 
    cout << endl;
}