What does it mean when we use a variable in C++ like a function with a default value as its parameter? [duplicate]

Question

I was reading a C++ code line. I encountered a weird code line where a variable was used as a function with a 0 as its parameter!

template <class T> class Stack {
    T data[50];
    int nElements;
public:
//This line is where the variable was used like a function!
    Stack() : nElements(0){}
    void push(T elemen);
    T pop();
    int tamanho();
    int isEmpty();
};

So what does exactly mean when we have: the constructor : private variable (0){}

This code line was very weird for me! Thanks

Answer 1

In the initializer_list of Stacks constructor, class member nElements is initialized with a value of zero upon creation of each Stack object.

The value 0 does not have any special meaning here, other than setting the initial number of elements for the Stack to zero as soon as it gets created and is empty.