What is the difference between call by value and call by reference in C?

Following are the differences between a call by value and call by reference are:

	Call by value	Call by reference
Description	When a copy of the value is passed to the function, then the original value is not modified.	When a copy of the value is passed to the function, then the original value is modified.
Memory location	Actual arguments and formal arguments are created in separate memory locations.	Actual arguments and formal arguments are created in the same memory location.
Safety	In this case, actual arguments remain safe as they cannot be modified.	In this case, actual arguments are not reliable, as they are modified.
Arguments	The copies of the actual arguments are passed to the formal arguments.	The addresses of actual arguments are passed to their respective formal arguments.

Example of call by value:

void change(int,int);
int main()
{
    int a=10,b=20;
    change(a,b); //calling a function by passing the values of variables.
    printf(“Value of a is: %d”,a);
    printf(“\n”);
    printf(“Value of b is: %d”,b);
    return 0;
}
void change(int x,int y)
{
    x=13;
    y=17;
}

Output:

Value of a is: 10
Value of b is: 20

Example of call by reference:

void change(int*,int*);  
int main()  
{  
    int a=10,b=20;  
    change(&a,&b); // calling a function by passing references of variables.  
    printf(“Value of a is: %d”,a);  
    printf(“\n”);  
    printf(“Value of b is: %d”,b);  
    return 0;  
}  

void change(int *x,int *y)  
{  
    *x=13;  
    *y=17;  
}

Output:

Value of a is: 13
Value of b is: 17