Question

How to insert new element at the beginning of forward_list in C++

Answer 1

#include <iostream>  
#include <forward_list> 

using std::forward_list;
using std::cout;

void printList(const forward_list<int>& flist)
{
	for (auto elem : flist) {
		cout << elem << ' ';
	}
	cout << std::endl;
}

int main()
{
	forward_list<int> flist = { 1, 2, 3, 4, 5 };

	flist.insert_after(flist.before_begin(), 888);

	printList(flist);

	return 0;
}

/*
run:

888 1 2 3 4 5

*/

 

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Answer 2

#include <iostream>  
#include <forward_list> 

using std::forward_list;
using std::cout;

void printList(const forward_list<int>& flist)
{
	for (auto elem : flist) {
		cout << elem << ' ';
	}
	cout << std::endl;
}

int main()
{
	forward_list<int> flist = { 1, 2, 3, 4, 5 };

	flist.push_front(999);

	printList(flist);

	return 0;
}

/*
run:

999 1 2 3 4 5

*/

 

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