C++ List insert

The insert function in C++ adds a new element right before the specified position, expanding the list container's size by the number of newly added elements.

Syntax

iterator insert( iterator pos, const value_type value);
void insert( iterator pos, int n, const value_type value);
void insert( iterator pos, InputIterator first, InputIterator last);

Parameter

It specifies the location where the new element will be inserted.

value : The value to be inserted.

n : Number of times the value to be occurred.

Specifies the range of elements to be added at the specified position pos within a container.

Return value

It yields an iterator referencing the recently created element.

Example 1

Let's see a simple example

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

Output:

In this instance, the iterator is directed to the initial element in the list. As a result, the number 5 is added prior to the first element of the list by employing the insert method.

Example 2

Let's see a simple example when n is given.

#include <iostream>
#include<list>
using namespace std;
int main()
{
   list<string> li={"C is a language"};
   list<string>::iterator itr=li.begin();
   li.insert(itr,2,"java ");
   for(itr=li.begin();itr!=li.end();++itr)
   cout<<*itr;
    return 0;
}

Output:

java java C is a language

In this instance, the insert method adds the string "java" twice prior to the initial element in the list.

Example 3

Let's see a simple example

#include <iostream>
#include<list>
using namespace std;

int main()
{
   list<int> li={1,2,3,4,5};
   list<int> li1={6,7,8,9};
   list<int>::iterator itr=li.begin();
   li.insert(itr,li1.begin(),li1.end());
   for(itr=li.begin();itr!=li.end();++itr)
{
   cout<<*itr;
   cout<<? ?;
              }                    
            return 0;
}

Output:

6 7 8 9 1 2 3 4 5

In this scenario, the range(first, last) within the list li1 is specified. Consequently, the insert method incorporates the elements within this specified range into the list li.