Question

I want put a value from front of the list into an another list but I am getting an error.

for exmaple

List<int> li;
List<int> li2;

.............
.............

li2.push_back(li.front()); // this statement doesnt work for me. 

Can someone please help me.

example code:

   list<int> li;
   list<int> li2;
   li.push_back(1);
   li.push_back(2);
   li.push_back(3);

   for(int i=0;i<3;i++)
   {

    cout<<li.front()<<endl;
    li2.push_back(li.pop_front());

   }

Answer 1

Also, Be aware that when the list is empty, the pop_front() and pop_back() will throw exceptions – resulting in segmentation fault. So it is mandatory to check the size of the list
i. directly – using the list function
ii.indirectly using the for loop as shown in the program.

Sample Code

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


int main( int argc, char *argv[])
{

    list<int> li;
    li.pop_front();

    return 0;
}

Ouput

-laptop:~/Study/Pgm$ ./test
Segmentation fault

I think this is the behaviour in all OS, I use g++ (4.4.1) on Linux platform.