Question

1) Given the following ‘generic’ program.

var aVar;

aVar = 10;

sub1();

function sub1 ()

{

    Sub2();

    Print (“ aVar = “ aVar + “\n”);

}

function sub2()

{

   var aVar;

   aVar = 4;

}

What would be output under static-scoping rules?

What would be output under dynamic-scoping rules?

2)

Discuss and compare the following memory allocation strategies for variables, give an example of how Java and/or Python uses each:

1. Stack-Dynamic
2. Explicit Heap-Dynamic
3. Implicit Heap-Dynamic

3) What is a descriptor? What are the required entries in a Java array descriptor for an int and when must they be stored (compile-time or run-time)? Compare this to a Python descriptor for an int.

4) Identify and explain the two common problems with C++ pointers?

Answer 1

to the toP Icvel viYonhyn man10 when we wil e Print Stakmn able rekrsto the most recent environment-一nina He 2Briets sPeak n Stack i used hor stathi memevr tor -ton-stati allocstion and hea dyne n1 varialles allocatd on stack q storid divety to te memery and hinu access to it is vers fastz Vaxiales allo cakd on the haP have hei numo allocakd at un time and hunu accesin this a bit glowey but tr he limited bsrnt Size of yǐY tual me ways This it much tallan tis oPaved to rt stick allocakt nmeYy Shot on OnePlus Powered by Dual Camera

3. java.io.FileDescriptor works for opening a file having a specific name. If there is any content present in that file it will first erase all that content and put “Beginning of Process” as the first line. Instances of the file descriptor class serve as an opaque handle to the underlying machine-specific structure representing an open file, an open socket, or another source or sink of bytes.

• The main practical use for a file descriptor is to create a FileInputStream or FileOutputStream to contain it.
• Applications should not create their own file descriptors.

4.

• Dynamically allocated block needs to be freed explicitly. Otherwise, it would lead to memory leak.
• Uninitialized pointers might cause segmentation fault.
• Arrays passed as a function parameter decay to a pointer to the first element of the array, obscuring whether the parameter is intended to point to an array or a single data element.