Question

can somebody please explain what is the difference between the following mechanisms of passing arguments: by value, by result, by result-value, with examples if possible, thanks in advance

Answer 1

For general info see Evaluation strategy.

For example code you can check HERE.

Also C# language specification can be useful :

5.1.4 Value parameters

A parameter declared without a ref or
out modifier is a value parameter. A
value parameter comes into existence
upon invocation of the function member
(method, instance constructor,
accessor, or operator) or anonymous
function to which the parameter
belongs, and is initialized with the
value of the argument given in the
invocation. A value parameter normally
ceases to exist upon return of the
function member or anonymous function.
However, if the value parameter is
captured by an anonymous function
(§7.15), its life time extends at
least until the delegate or expression
tree created from that anonymous
function is eligible for garbage
collection. For the purpose of
definite assignment checking, a value
parameter is considered initially
assigned.

5.1.5 Reference parameters

A parameter declared with a ref
modifier is a reference parameter. A
reference parameter does not create a
new storage location. Instead, a
reference parameter represents the
same storage location as the variable
given as the argument in the function
member or anonymous function
invocation. Thus, the value of a
reference parameter is always the same
as the underlying variable. The
following definite assignment rules
apply to reference parameters. Note
the different rules for output
parameters described in §5.1.6.

• A variable must be definitely assigned
  (§5.3) before it can be passed as a
  reference parameter in a function
  member or delegate invocation.

• Within a function member or anonymous function, a reference
  parameter is considered initially
  assigned.

Within an instance method or instance
accessor of a struct type, the this
keyword behaves exactly as a reference
parameter of the struct type (§7.6.7).

5.1.6 Output parameters

A parameter declared with an out
modifier is an
output parameter. An output parameter
does not create a new storage
location. Instead, an output parameter
represents the same storage location
as the variable given as the argument
in the function member or delegate
invocation. Thus, the value of an
output parameter is always the same as
the underlying variable. The following definite
assignment rules apply to output
parameters. Note the different rules
for reference parameters described in
§5.1.5.

• A variable need not be definitely assigned before it can be passed as
  an output parameter in a function
  member or delegate invocation.
• Following the normal completion of a function member or delegate
  invocation, each variable that was
  passed as an output parameter is
  considered assigned in that execution
  path.
• Within a function member or anonymous function, an output
  parameter is considered initially
  unassigned.
• Every output parameter of a function member or anonymous
  function must be definitely
  assigned (§5.3) before the function
  member or anonymous function
  returns normally.

Within an instance constructor of a
struct type, the this keyword behaves
exactly as an output parameter of the
struct type (§7.6.7).