understand passing parameters by reference with dynamic allocation

Question

I\'m trying understand how to pass a parameter by reference in C language. So I wrote this code to test the behavior of parameters passing:

#include 

        

Answer 1

See, what's happened in first program.

Before call to alocar we have just variable n in main, pointing to some undefined place:

 main()::n [  X--]--->(?)

(there's value in square brackets, which is undefined, marked as X). Then we call alocar, and we have another variable in alocar's scope, which have a copy of origianl var.

 main()::n   [  X--]--->(?)
 alocar()::n [  X--]-----^

Now, allocate some memory:

 main()::n   [  X--]--->(?)
 alocar()::n [  *--]--->[   Y  ]

Assign value to allocated var:

 main()::n   [  X--]--->(?)
 alocar()::n [  *--]--->[  12  ]

Return. alocar()::n is removed as it live only while alocar() is executed.

 main()::n   [  X--]--->(?)
                        [  12  ]

main()::n is still pointing to some undefined place... (Which possibly stores value 0) And no one points to allocated place.