Answers for "stl queue in c++"

queue stl

#include <iostream>
#include<queue>
#include<algorithm>

using namespace std;

int main()
{
    queue<int>q;
    q.push(10);
    q.push(5);
    q.push(15);
    while(!q.empty())
    {
        cout<<q.front()<<" ";
        q.pop();
    }
    cout<<endl;
    cout<<"_------------------------"<<endl;
    q.push(10);
    q.push(5);
    q.push(15);
    queue<int>q2;
    q2.push(100);
    q2.push(200);
    q2.push(300);
    q2.push(400);
    q.swap(q2);
    while(!q.empty())
    {
        cout<<q.front()<<" ";
        q.pop();
    }

    return 0;
}

template queue in c

#define define_list(type) 

    struct _list_##type; 
    
    typedef struct 
    { 
        int (*is_empty)(const struct _list_##type*); 
        size_t (*size)(const struct _list_##type*); 
        const type (*front)(const struct _list_##type*); 
        void (*push_front)(struct _list_##type*, type); 
    } _list_functions_##type; 
    
    typedef struct _list_elem_##type 
    { 
        type _data; 
        struct _list_elem_##type* _next; 
    } list_elem_##type; 
    
    typedef struct _list_##type 
    { 
        size_t _size; 
        list_elem_##type* _first; 
        list_elem_##type* _last; 
        _list_functions_##type* _functions; 
    } List_##type; 
    
    List_##type* new_list_##type(); 
    bool list_is_empty_##type(const List_##type* list); 
    size_t list_size_##type(const List_##type* list); 
    const type list_front_##type(const List_##type* list); 
    void list_push_front_##type(List_##type* list, type elem); 
    
    bool list_is_empty_##type(const List_##type* list) 
    { 
        return list->_size == 0; 
    } 
    
    size_t list_size_##type(const List_##type* list) 
    { 
        return list->_size; 
    } 
    
    const type list_front_##type(const List_##type* list) 
    { 
        return list->_first->_data; 
    } 
    
    void list_push_front_##type(List_##type* list, type elem) 
    { 
        ... 
    } 
    
    _list_functions_##type _list_funcs_##type = { 
        &list_is_empty_##type, 
        &list_size_##type, 
        &list_front_##type, 
        &list_push_front_##type, 
    }; 
    
    List_##type* new_list_##type() 
    { 
        List_##type* res = (List_##type*) malloc(sizeof(List_##type)); 
        res->_size = 0; 
        res->_first = NULL; 
        res->_functions = &_list_funcs_##type; 
        return res; 
    }

#define List(type) 
    List_##type

#define new_list(type) 
    new_list_##type()