Declaring a pointer, int *ptr vs int ptr

The following code works

Code:

---

#include <iostream>

using namespace std;

int main()
{
        int a = 1;
        int *b;
       
        b = &a;
       
        cout << " a is:" << a  << endl;
        cout << " &a is:" << &a  << endl;
        cout << " b is:" << b  << endl;
        cout << " *b is:" << *b  << endl;
       
        return 0;
}

---

If I change "int *b" to "int b," as shown below, then the code does not compile. Why is this? What exactly does the statement "int *b declare?"

Code:

---

#include <iostream>

using namespace std;

int main()
{
        int a = 1;
        int b;
       
        b = &a;
       
        cout << " a is:" << a  << endl;
        cout << " &a is:" << &a  << endl;
        cout << " b is:" << b  << endl;
        cout << " *b is:" << *b  << endl;
       
        return 0;
}

---

int* b declares a pointerr to int;

b is a variable able to store the address of some int variable

b = &a; takes the address of a and stores it in the b

"int *b;" declares a pointer that can point to an object of type int.
"int b;" declares an int (a signed integer, generally 16 to 64 bits depending on your compiler and environment). It's not a pointer, and certainly not a pointer to another int.
Have you read the tutorials on pointers on the main site?
(edit: vart beat me to it)