Answer / ravi s. sharma

In call by value, a copy of value known as(actual argument)
is passed to the function known as(formal argument). Both
values are stored at different locations and scope. The
changes made in a copy(formal argument) does not affect the
original value(actual argument).

In call by reference, a reference/address of variable known
as(actual argument) is passed to the function known
as(formal argument) which is stored in a
pointer/ref.variable. The changes made in a function
(through pointer/ref. variable) affect the original
value(actual argument).

Answer / shashi shekhar

For instance consider program1

main()
{
int x=50, y=70;
interchange(x,y);
printf(“x=%d y=%d”,x,y);
}

interchange(x1,y1)
int x1,y1;
{
int z1;
z1=x1;
x1=y1;
y1=z1;
printf(“x1=%d y1=%d”,x1,y1);
}

Here the value to function interchange is passed by value.

Consider program2

main()
{
int x=50, y=70;
interchange(&x,&y);
printf(“x=%d y=%d”,x,y);
}

interchange(x1,y1)
int *x1,*y1;
{
int z1;
z1=*x1;
*x1=*y1;
*y1=z1;
printf(“*x=%d *y=%d”,x1,y1);
}

Here the function is called by reference. In other words
address is passed by using symbol & and the value is
accessed by using symbol *.

The main difference between them can be seen by analyzing
the output of program1 and program2.

The output of program1 that is call by value is
x1=70 y1=50
x=50 y=70

But the output of program2 that is call by reference is

*x=70 *y=50
x=70 y=50

This is because in case of call by value the value is passed
to function named as interchange and there the value got
interchanged and got printed as

x1=70 y1=50

and again since no values are returned back and therefore
original values of x and y as in main function namely

x=50 y=70 got printed.

But in case of call by reference address of the variable got
passed and therefore what ever changes that happened in
function interchange got reflected in the address location
and therefore the got reflected in original function call in
main also without explicit return value. So value got
printed as *x=70 *y=50 and x=70 y=50

Answer / m.vairalkar

It is not difference
but good thing..Both tha
techniques r good ..if we want
changes then use call by refernce
otherwise use call by value

Answer / prateek g

The call by value system copies the actual parameters to
actual parameters and then uses them i.e. the function
creates its own copy of values, any change in
these values will not be reflected
in the original values.
The call by reference system refers the actual parameters
i.e. these doesn’t creates a copy of original parameters,
any change in these parameters will be reflected back in
original parameters.

Answer / varsha jarwal

In call by value:-
since new location is created, this method is slow.
In call by reference:-
since the existing memory location is used through its
address, this method is fast.

Answer / pasang tsering

call by value:-value of the actual argument passed to the
formal arguments.
call by reference:-address of the actual arguments passed
to the fomal arguments.

Answer / atul gupta

call by value: copies the value of argument into the formal
parameter.Any changes made in the parameter does not affect
the argument .

call by reference : copies the address of argument into the
formal parameter . The address will access the actual argument
used in the call . so any changes made in the parameter will effect the argument

Answer / vino

Mostly  call by value and call by reference is differ  from 
copy and modify process..
Copy:
Call by value:
It take difference memory locations  for variables.Duplicate copy of the original parameter is passed.
Call by reference:
It takes Same memoy locations for  variables.Actual copy of the original parameter is passed.
Modify:
Call by value:
No affect on original parameter after modifying the parameter in functions.
Call by reference:
original parameter can be affect afetr modifying the parameter in function..

Answer / meghanchal kumar dixit

call by value-
If we call a function in C  by passing values of variables as the parameters/arguments to the function then such type of function call is known as Call by value.

call by reference-A function by passing addresses of variables as the parameters to the function is known as Call by Reference.

Answer / aishwarya kulkarni

In call By Value it create different memory for local
variable and actual called Variable. so changes does not
affect to the actual variable.

Call By Reference:
In call By Reference Compiler create same memory location
for the local variable and actual called variable so changes
affect to the actual variable and modify the value of actual
called Variable.

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