call by value and call by reference

 Brief call by value and call by reference in detail. (MAY 2009)

Call by value:
In call by value the value of the actual arguments are passed to the formal arguments and the operation is done on formal arguments.
Example program:
· To send two integer values using “call by value”.
Call by reference:
In call by reference the address of actual argument values are passed to formal argument values.
Example program:

· To send a value by reference to user defined function.

FUNCTIONS

What are functions? Explain the types of functions in detail with an example program for each type.

A function is a self contained block or a sub program of one or more statements that performs a special task when called.
Types:
· Library Functions
· User Defined functions
(a) Function Declaration
returntype function-name(Parameters);
Example:
int square(int, int);
(b) Function calling
function-name(actual parameters);
Example:
int square(a,b);

(c) Function Definition:
returntype function-name(formal parameters)
{
}

Example:
local variable declaration;
statement 1; statement 2; return(value);
void square(int a, int b)
{
printf(“%d”,(a*b));
}
Example for functions:
· Addition of two numbers where addition is a separate function
· Program using function for evaluating Fibonacci series.