When declaring a variable in C++/C

Question

When I declare a variable, such as:

 int x = 6;

What exactly is x? an address in the memory is usually hexadecimal..
Also, when I'm calling X

x = 2;

How does the compiler know where x is? x isn't an address.

That was my first question.

Second:
Let's say i have an object:
Person p;
p has 2 datamembers:

 int type1, int type2;

What exactly is p, and why do I need to go to p, then the variable?

p.type1, p->type1.

Answer 1

In the case int x = 6, x is just a name to help you write the code and the compiler compile it. It's basically an alias for some place in memory, so that it's easier to access it later via x = 2 - this tells both you and the compiler that you want to write the value 2 in that same place.

Same as before, but it takes up more space (sizeof(Person) to be exact). p->type1 is only valid if p is a pointer to a Person (or if you overloaded the -> operator, but it's not the case), p.type1 is the syntax used for an object, to specify which part of the it you want to access.

Answer 2

int x=6 ;

Here x is identifier i.e. the name given to memory area where value 6 is stored.
x is simple name just to identify memory area where value 6 is stored.
when u declares variable, that time compiler stores ur variable name in the identifier table.

For person p, here once again p is name given to the memory area,which stores two data member type1 & type2

For accessing the value of type1 & type2, first u have to find the memory area, where they are stored. That's why u have to first access the memory area p & then u can access type1 * type2