call by value mechanism is same in any programming language.
The apply the call by
value in a function, you have to use the formal parameter specification
as per call by value. The language tells you how to specify for call by
value or call by reference mechanisms. You have to follow that way as
told by the rule of the language.
It is the default mechanism in a
programming language, in general. You just have to write the
variable name (identifier) or expression as the parameter of the function,
when calling the function.
Suppose you have a function defined as follows.
integer My_add( integer A,
C = A + B ;
A = 10; B = 7;
In the main program you call the function by the
following procedural (sequential control) statement.
integer X, Y, Z ;
X = 5;
Y = 4 ;
Z = My_add ( X, Y) ;
you can also write : Z =
My_add (5, 4);
Here the formal parameters A and B in the
function My_add are call by value parameters. The parameters X and Y in
the main program will not be changed after the addition function is executed.
Thus even the commented statements in the
function are executed, the values of X and Y in the main program do not change.