CS 4100 Dr. Melanie Martin March 15, 2007

Today Finish up some FORTRAN Assignment 3 Final Project Fun with GOTO Office hours cancelled today so I can go to doctor

FORTRAN Name Structures Recall that when variables are declared –(of course, this is optional!) –INTEGER I, J, K –Storage is allocated Only once and never changes Names bound to address Takes place before execution STATIC Now in most languages allocation is DYNAMIC

Now: Semantics (meaning) “They went to the bank of the Rio Grande.” What does this mean? How do we know? CONTEXT, CONTEXT, CONTEXT

Programming Languages X = COUNT(I) What does this mean –X integer or real –COUNT array or function Again Context –Set of variables visible when statement is seen Context is called ENVIRONMENT

SCOPE Scope of a binding of a name –Region of program where binding is visible In FORTRAN –Subprogram names GLOBAL Can be called from anywhere –Variable names LOCAL To subprogram where declared

Next Time We’ll work through an example of scoping and draw the contour diagram That will finish what we’re doing with FORTRAN Algol is next!

Project Read through handout and ask questions We will have a plagiarism discussion soon

Assignment 3 Read over and ask questions Topics list is just to give you an idea

GOTO Read Dijkstra’s letter In groups of 3 or 4 students –Outline his arguments –Discuss each argument Do you agree or disagree –Over the years, folks have had strong feelings both ways Expand or rebut each main point –Use “evidence” whenever possible

GOTO Today –Hand in a copy of your group outline with indication of whether the group agrees or disagrees –Tuesday hand in an individual write-up