error while inserting a node at end of a linked list

Question

SinglyLinkedListNode* insertNodeAtTail(SinglyLinkedListNode* head, int data) {
    if(head==NULL)
    {
        SinglyLinkedListNode* tmp=new SinglyLinkedListNode();
        tmp->data=data;
        tmp->next=NULL;
        head=tmp;
        return head;
    }
    else
    {
        insertNodeAtTail(head->next,data);
    }
}

these are the errors which the compiler is giving after compilation.

solution.cc: In function ‘SinglyLinkedListNode* insertNodeAtTail(SinglyLinkedListNode*, int)’:
solution.cc:60:60: error: no matching function for call to ‘SinglyLinkedListNode::SinglyLinkedListNode()’
         SinglyLinkedListNode* tmp=new SinglyLinkedListNode();
                                                            ^
solution.cc:10:9: note: candidate: SinglyLinkedListNode::SinglyLinkedListNode(int)
         SinglyLinkedListNode(int node_data) {
         ^~~~~~~~~~~~~~~~~~~~
solution.cc:10:9: note:   candidate expects 1 argument, 0 provided
solution.cc:5:7: note: candidate: constexpr SinglyLinkedListNode::SinglyLinkedListNode(const SinglyLinkedListNode&)
 class SinglyLinkedListNode {
       ^~~~~~~~~~~~~~~~~~~~
solution.cc:5:7: note:   candidate expects 1 argument, 0 provided
solution.cc:5:7: note: candidate: constexpr SinglyLinkedListNode::SinglyLinkedListNode(SinglyLinkedListNode&&)
solution.cc:5:7: note:   candidate expects 1 argument, 0 provided
solution.cc:72:1: error: control reaches end of non-void function [-Werror=return-type]
 }
 ^

Answer 1

You don't have a default constructor for SinglyLinkedList, but you have a constructor that takes an int. You are also not returning anything from your else block.

You should also prefer to use nullptr instead of NULL for pointer comparison.

SinglyLinkedListNode* insertNodeAtTail(SinglyLinkedListNode* head, int data) {
    if(head==nullptr) //Use nullptr
    {
        SinglyLinkedListNode* tmp=new SinglyLinkedListNode(data); //Construct with data
        tmp->data=data; //This line can probably be removed now?
        tmp->next=NULL;
        head=tmp;
        return head;
    }
    else
    {
        return insertNodeAtTail(head->next,data); //Make sure to return here aswell
    }
}