How to explain C pointers (declaration vs. unary operators) to a beginner?

Question

I have had the recent pleasure to explain pointers to a C programming beginner and stumbled upon the following difficulty. It might not seem like an issue at all if you alre

Answer 1

The 2nd statement int *bar = &foo; can be viewed pictorially in memory as,

   bar           foo
  +-----+      +-----+
  |0x100| ---> |  1  |
  +-----+      +-----+ 
   0x200        0x100

Now bar is a pointer of type int containing address & of foo. Using the unary operator * we deference to retrieve the value contained in 'foo' by using the pointer bar.

EDIT: My approach with beginners is to explain the memory address of a variable i.e

Memory Address: Every variable has an address associated with it provided by the OS. In int a;, &a is address of variable a.

Continue explaining basic types of variables in C as,

Types of variables: Variables can hold values of respective types but not addresses.

int a = 10; float b = 10.8; char ch = 'c'; `a, b, c` are variables. 

Introducing pointers: As said above variables, for example

 int a = 10; // a contains value 10
 int b; 
 b = &a;      // ERROR

It is possible assigning b = a but not b = &a, since variable b can hold value but not address, Hence we require Pointers.

Pointer or Pointer variables : If a variable contains an address it is known as a pointer variable. Use * in the declaration to inform that it is a pointer.

• Pointer can hold address but not value
• Pointer contains the address of an existing variable.
• Pointer points to an existing variable