Difference between call by value and call by reference?

Answer 1

Pass by value is the regular way you would pass a variable through a function:

void seta(int a)
{
a = 10;
}

int main()
{
int a = 5;
seta(a);
cout << a;
//output is 5, because the function created a copy of variable a from main
}

Pass by reference is when you pass through a variable when the function parameters are that of a memory address using the ampersand (&):

void seta(&a)
{
a = 10;
}

int main()
{
int a = 5;
seta(a);
cout << a;
//output is 10, as we passed by reference, allowing the function to modify the variables memory address, rather than creating a copy and modifying that
}

Answer 2

call by value: the value of the variable is copied when passed
call by reference: the parameter is a reference to the variable passed, and the variable can be modified directly through it.

An example of call by reference:
void swap(int &a, int &b) {
int tmp;
tmp = a;
a = b;
b = tmp;
}
This function swaps the value of two variables.

Answer 3

in caal by value we pass value as a variable. while in caal by reference we pass the address as a refernce