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c++pointersmemorystructure

how does pointer to structure works?

I know about pointer of variables.

int  x = 10;
int *ptr = &x;

In these expression three things involved:

  1. x takes 2 byte of memory because it is an integer.

  2. ptr takes 2 bytes also.

  3. If memory address of x is 1004, then ptr will stores 1004.

In these example whenever we use *ptr in program, It give us a value which stored at memory addrs - 1004

But what happens in structure? Let take example:

struct book {
int a;
int b;
}
struct book str1, str2;
struct book *ptr = &str1;

I have three question about this example:

  1. How does ptr holds complete address of str1?

  2. What is the difference between pointer to variable and pointer to complete structure in memory?

  3. How many bytes ptr will take?

  4. Do ptr have members? If it have members so what type of members it will have? (Pointer or variable)

and one more thing- what does with object of classes instead of it

Solution

  • 1) how does ptr holds complete addrs of str1?

    It holds the starting address. It doesn't need to hold a range or anything.

    2) how would be architecture of ptr in memory?

    Internally it's a 32-bit or 64-bit unsigned integer depending on the operating system bitwidth (interpreted as a pointer).

    3) how many bytes ptr will take?

    4 or 8 bytes (for a 32- or 64-bit OS).

    4) do ptr have members? If it have members so what type of members it will have? (Pointer or variable)

    You can dereference the pointer using the -> operator as in

    int x = ptr->a;