C++ Usage and example of List merge()

C++ List (List)

C ++ The List merge() function merges two sorted lists in ascending order. It merges the y list into the given list container, removing all elements from y.

Two possible situations may occur in the merge() function of the merge function:

If no comparator is passed in the parameters, two sorted lists will be merged into one list.

If a comparator is passed in the parameters, the list will be merged according to its internal comparison.

Syntax

two lists list1and list2.Syntax is:

list1.merge(list2);
list1.merge(list2,compare);

parameters

list2: To be merged with list1The merged list.

compare: This is a comparator function object used to compare the value of the first parameter with the value of the second parameter. If the value of the first parameter is less than the value of the second parameter, it returns true; otherwise, it returns false.

Return value

It does not return any value.

Example1

Let's look at a simple example

Example

#include <iostream>
#include<list>
using namespace std;
int main()
{
　　　list<int> li={1,2,3,4});
　　　list<int> li1={5,6,7,8});
　　　li.merge(li1);
　　　for(list<int>::iterator itr = li.begin(); itr != li.end();++itr){
　　　　　　　std::cout <<　*itr << "  " << std::endl;　　
　　　}　　　
　　　return 0;
}

Output:

1　2　3　4　5　6　7　8

In this example, the merge() function will merge the list li with the list li1Merge into a list.

Example2

Let's look at a simple example when the comparator is passed as a parameter

Example

#include <iostream>
#include<list>
using namespace std;
bool comparison(int first, int second)
{
　　　　bool a;
　　　　a = first < second;
　　　　return (a);
}
int main()
{
　　list<int> li={9,10,11});
　　list<int> li1={5,6,7,15});
　　li.merge(li1,comparison);
　　for(list<int>::iterator itr = li.begin(); itr != li.end();++itr){
　　　　　　std::cout <<　*itr << " " << std::endl;
　　}　　
　　return 0;
}

Output:

5　6　7　9　10　11　15

In this example, the merge() function merges the lists based on the internal comparison.

C++ List (List)