函数无法识别我在 C++ 中传递节点指针向量？

Question

I'm pretty new to C++, for a binary tree project, I am trying to pass a vector of node pointers into a function that will add/manipulate the tree. The errors are commented below.

Example of one of the function's signatures:

void add(vector <Node*> &nodes, int &Aindex, vector <int> A, int value, vector <int> E, int Eindex);

Main code:

vector <Node*> makeTree(vector <int> A, vector <int> E) {
    vector <Node*> nodes = {};
    int Aindex = 0;
    for (int i = 0; i < E.size(); i++) {
        if (i == 0 || i % 2 != 0) {
            if (i == 0) {
                create(nodes, Aindex, A, E[i]); // no matching function to call to ERROR.
            } else {
                add(nodes, Aindex, A, E[i], E, i); // no matching function to call to ERROR.
            }
            Aindex++;
        } else {
            if (find(nodes, Aindex, A, E[i]) == false) { // no matching function to call to ERROR.
                create(nodes, Aindex, A, E[i]); // no matching function to call to ERROR.
                Aindex++;
            } else {

            }
        }
    }
    return nodes;
}

Answer 1

Make sure that, if those functions aren't in the same file as your "Main code", that they are visible by means some of sort of include .

Edit: As pointed out by @QuentinUK, these functions, or their prototypes at least, need to appear before they are called.