function - Parameter Passing in C - Pointers, Addresses, Aliases -

could please explain difference between parameter passing in c please? according professor notes there 4 different ways pass parameters

1. call-by-value
2. call-by-address (pointer)
3. call-by-alias
4. global variable / static variable

if please give example, appreciate that, , work commended.

1. call-by-value

   passing value function parameter. if function modifies variable, actual variable won't changed.

   void fun1(int myparam) {     myparam = 4; }  void main() {     int myvalue = 2;     fun1(myvalue);     printf("myvalue = %d",myvalue); } 

   myvalue 2.

2. call-by-address (pointer)

   void fun1(int *myparam) {     *myparam = 4; } void main() {     int myvalue = 2;     fun1(&myvalue);     printf("myvalue = %d",myvalue); } 

   here passing address of myvalue fun1. value of myvalue 4 @ end of main().

3. call-by-alias

   there no alias in c per understanding. should c++ reference mechanism.

4. global variable / static variable

   global , static variables variables stored in common places, accessible caller , callee functions. both caller , callee able access , modify them.

   int myvalue = 2; void fun1() {     myvalue = 4; } void main() {     myvalue = 2     fun1();     printf("myvalue = %d",myvalue); } 

   as can guess, value of myvalue 4 @ end of main().

hope helps.