The * (indirection) operator determines
the value referred to by the pointer-type operand. The operand can be a pointer to an incomplete type that
is not cv void. The lvalue thus obtained cannot be
converted to a 
prvalue
rvalue. If the operand points to an object, the operation
yields an lvalue referring to that object. If the operand points
to a function, the result is 
a function
designator
an lvalue referring
to the object to which the operand points
. Arrays and
functions are converted to pointers.
The type of the operand determines the type of the result. For example, if the operand is a pointer to an int, the result has type int.
Do not apply the indirection operator to any pointer that contains an address that is not valid, such as NULL. The result is not defined.
p_to_y = &y;
*p_to_y = 3;