1. Introduction to programming languages, Algorithms & flowcharts
Slides borrowed from Instructor: Wajih Alouini

2. What are Program and programming language?
Program : Set of instructions which a computer can “interpret” to solve problems, make calculations, perform tasks, etc.
Programming Language : A formal language that is intended for the expression of computer programs
Syntax is away of writing program in any language (every language has its own syntax)
Slides borrowed from Instructor: Wajih Alouini

3. Why study programming languages?
Programming languages are important for students in all disciplines of engineering because they are the primary tools of the central activity of any science.
Slides borrowed from Instructor: Wajih Alouini

4. Why study programming languages? (cont.)
To improve your ability to develop effective algorithms and to improve your use of your existing programming language.
To increase your vocabulary of useful programming constructs.
To allow a better choice of programming languages.
To make it easier to learn a new language.
Slides borrowed from Instructor: Wajih Alouini

5. A short history of programming Languages
1950 : Numerically based languages. FORTRAN (55)
Business languages. COBOL(60)
Artificial intelligence languages. LISP, ALGOL(58)
LISP, FORTRAN (55) ALGOL
1970 : PLs Ada, C, Pascal, Smalltalk
1980 : Development of functional programming: ML, Miranda
Object-oriented programming: Smalltalk, C++
Slides borrowed from Instructor: Wajih Alouini

6. A short history of programming languages (cont.)
Fourth-generation languages
Productivity tools (such as spreadsheets)
Visual languages : Delphi
Scripting languages : Perl
Expert systems shells
Network computing : Java
Slides borrowed from Instructor: Wajih Alouini

7. Low-level vs. High-level Programming Languages
Machine code
Assembly
High-level: (abstraction from the computer details)
Basic, C, Java, Pascal, C++, Perl, Python, …
Slides borrowed from Instructor: Wajih Alouini

8. Styles of Computer Programming
Procedural: procedures, routines, subroutines, methods, or functions
e.g. C, Pascal, Basic, Fortran
Functional
Mathematical functions
e.g. Lisp, Erlang, Haskell, ML, …
Object-oriented
e.g. C++, Java, Smalltalk
Rule-based (or Logic) : facts, rules
e.g. Prolog
Slides borrowed from Instructor: Wajih Alouini

9. Slides borrowed from Instructor: Wajih Alouini
Examples (1/5)
Fibonacci numbers
Fn = Fn-1 + Fn-2 , n>=2 F0 = 0, F1 = 1
How to program?
0,1,1,2,3,5,8,13
Slides borrowed from Instructor: Wajih Alouini

10. Slides borrowed from Instructor: Wajih Alouini
Examples (2/5)
Functional: (Haskell)
fib 0 = 0 fib 1 = 1 fib n = fib (n-1) + fib (n-2)
Slides borrowed from Instructor: Wajih Alouini

11. Slides borrowed from Instructor: Wajih Alouini
Examples (3/5)
Procedural: (C)
int fib(int n) { int first = 0, second = 1; for (int i=0, i<n; i++) { int sum = first+second; first = second; second = sum; } return first; }
Slides borrowed from Instructor: Wajih Alouini

12. Slides borrowed from Instructor: Wajih Alouini
Examples (4/5)
Assembly: (in x86 using MASM syntax)
mov edx, [esp+8] cmp edx, 0 mov eax, 0 ret cmp edx, 2 mov eax, 1 ret push ebx mov ebx, 1 mov ecx, 1 lea eax, [ebx+ecx] cmp edx, 3 mov ebx, ecx mov ecx, eax dec edx pop ebx ret
Slides borrowed from Instructor: Wajih Alouini

13. Slides borrowed from Instructor: Wajih Alouini
Examples (5/5)
Machine code
8B FA B C383 FA B C353BB B D FA BD98B C84AEBF1 5BC3
Slides borrowed from Instructor: Wajih Alouini

14. Attributes of a good language
Ease of program verification
Proof of correctness, desk checking, test
Simplicity of semantic and syntax
Programming environment
Portability of programs
Cost of use
Program execution
Program translation
Program creation, testing, and use
Program maintenance
Slides borrowed from Instructor: Wajih Alouini

15. Slides borrowed from Instructor: Wajih Alouini
Attributes of a good language (another view: to make a software reliable, maintainable, efficient)
Reliability
Writability
Readability
Simplicity
Safety (no goto, no pointers)
Robustness (undesired events can be trapped, like arithmetic overflow, invalid inputs)
Maintainability
Factoring (modularity)
Locality
Efficiency
Slides borrowed from Instructor: Wajih Alouini

16. Issues for all Languages
Can it be understood by people and processed by machines?
although translation may be required
Sufficient expressive power?
can we say what needs to be said, at an appropriate level of abstraction?
Slides borrowed from Instructor: Wajih Alouini

17. Slides borrowed from Instructor: Wajih Alouini
Translation
Compilation
Translate into instructions suitable for some other (lower level) machine
During execution, that machine maintains program state information
Interpretation
May involve some translation
Interpreter maintains program state
Slides borrowed from Instructor: Wajih Alouini

18. Slides borrowed from Instructor: Wajih Alouini
Trade-offs
Compilation
lower level machine may be faster, so programs run faster
compilation can be expensive
examples: C (and Java?)
Interpretation
more ability to perform diagnostics (or changes) at run-time
examples: Basic, UNIX shells, Lisp
Slides borrowed from Instructor: Wajih Alouini