将指向对象的指针添加到向量

Question

I am trying to add pointers to an object to a vector in a function like this:

vector:

vector<struct Node*> vars;

function:

void fill_vec(){
    struct Node* temp;
    temp = new Node();
    cout << token << endl;
    temp->name = token;
    temp->value = 0;
    cout << temp << endl;
    vars.push_back(temp);
}

fill_vec is being called in a while loop that stops when there aren't anymore variable names.

It is adding the correct amount of nodes to the vector, but everything is pointing to the same object. Token is being parsed.

output of above:

a
0x9c6010
b 
0x9c6050

printing vector:

void print_vars(){
    for(int i = 0; i < vars.size(); i++){
        cout << "Name:" << vars[i]->name << endl;
        cout << "Value:" << vars[i]->value << endl;
    }
}

output:

Name:b
Value:0
Name:b
Value:0

My thought was that when I allocated new memory, the address would change. When I print the address of temp each time I call the function, the address is the same . I was printing the address wrong. The address is different for each call of the function. Thank you in advance for the help.

Answer 1

My thought was that when I allocated new memory, the address would change.

It does indeed.

When I print the address of temp each time I call the function, the address is the same.

That is because you are printing out the address of a local variable, which happens to reside at the same stack memory address each time fill_vec() is called. You should be printing out the memory address of the allocated Node instead.

Change this line:

cout << &temp << endl;

To this:

cout << temp << endl;

Answer 2

As it turns out, it was the token. Token is a char* and I was not using strdup() on it. So every time I updated token, name was being changed in each object.