In this guide, we will explore the forwardlist::emplacefront method in C++ along with its syntax and illustrations.
In C++ STL, a forward list represents a singly linked list data structure. This implementation, introduced in C++11, offers advantages over other container types for tasks like insertion, deletion, and reordering operations (like sort) due to its ability to perform these actions in constant time. Unlike the list container, the forward list only needs to keep track of the location of the next element, as opposed to both the next and previous elements.
Syntax:
It has the following syntax:
forward_list::emplace_front()
The function mentioned is utilized for inserting a fresh element into the forward-looking list container, appending the new element at the beginning of the forward list.
forwardlistname.emplace_front(value)
The object that needs to be added to the forward list is referred to as the parameter value.
Result: The parameter is added to the beginning of the linked list.
Examples:
Input: myList{1, 2, 3, 4, 5};
myList.emplace_front(0);
Output: myList = 0, 1, 2, 3, 4, 5
Input: myList{};
myList.emplace_front(9);
Output : myList = 9
Exceptions and Errors
- It provides a strong exception assurance, so if an exception is thrown, no modifications are made.
- The argument must be of the same type as the container, and an error will be generated.
Example 1:
Filename: forward.cpp
//Example an integer forward list
// A C++ program to demonstrate the emplace() method implementation.
#include <forward_list>
#include <iostream>
using namespace std;
int main() {
forward_list<int> mylist;
mylist.emplace_front(8);
mylist.emplace_front(9);
mylist.emplace_front(10);
mylist.emplace_front(11);
mylist.emplace_front(12);
mylist.emplace_front(13);
//The final mylist becomes 13,12,11,10,9,8
// display of the list
for (auto ite = mylist.begin(); ite != mylist.end(); ++ite)
cout << ' ' << *ite;
return 0;
}
Output:
13 12 11 10 9 8
Example 2:
Filename: ForwardInt.cpp
//Example of an String Forward list
//A C++ program to demonstrate the emplace() method implementation.
#include <forward_list>
#include <iostream>
#include <string>
using namespace std;
int main() {
forward_list<string> mylist;
mylist.emplace_front("Standards");
mylist.emplace_front("Languages");
mylist.emplace_front("Programming");
//The mylist becomes Programming Languages Standards
// display of the result
for (auto it = mylist.begin(); it != mylist.end(); ++it)
cout << ' ' << *it;
return 0;
}
Output:
Programming Languages Standards
Example 3:
Filename: ForwardList.cpp
// Example of char Forward list
// A C++ program to demonstrate the emplace() method implementation.
#include <forward_list>
#include <iostream>
using namespace std;
int main() {
forward_list<char> mylist;
mylist.emplace_front('n');
mylist.emplace_front('m');
mylist.emplace_front('l');
mylist.emplace_front('k');
mylist.emplace_front('j');
//The forwarded mylist becomes j k l m n
// display of the result
for (auto iterator = mylist.begin(); iterator != mylist.end(); ++iterator)
cout << ' ' << *iterator;
return 0;
}
Output:
j k l m n
Example 4:
Filename: forwardApplication.cpp
// A C++ program to demonstrate the emplace() method implementation.
#include <forward_list>
#include <iostream>
using namespace std;
int main() {
forward_list<int> mylist{};
mylist.emplace_front(43);
mylist.emplace_front(27);
mylist.emplace_front(93);
mylist.emplace_front(45);
mylist.emplace_front(21);
mylist.emplace_front(32);
//the mylist becomes
//32 21 45 93 27 43
// sorting function
mylist.sort();
for (auto ite = mylist.begin(); ite != mylist.end(); ++ite)
cout << ' ' << *ite;
}
Output:
21 27 32 43 45 93
