- Value parameters: the function receives a copy of the value of the actual parameter (pass by value)

- Changing the values of the formal parameters does not affect the values of the actual parameters !!

- Reference parameters: the function receives a copy of the address of the actual parameter (pass by reference)

- When the address of a parameter is passed to a function, an ampersand (&) must be attached at the end of the parameter's datatype

- Changing the values of the formal parameters does affect the values of the actual parameters !!

- In pass by value, any expression can be passed to a function but in pass by reference, only the address of a variable can be passed to a function

void compute_sum(int,int,int&)
void main()
{
int x,y,sum;

x=10; y=20;
compute_sum(x,y,sum);
compute_sum(2*x-1, y-15, sum);
}

void compute_sum(int num1, int num2, int& res)
{
res = num1 + num2;
}