C++ Crash Course Class 1 What is programming?

What’s this course about? Goal: Be able to design, write and run simple programs in C++ on a UNIX machine.

What’s this course about? Goal: Be able to design, write and run simple programs in C++ on a UNIX machine. Also: understand what it means to program, understand a bit better how computers work, and be better equipped with the ability to learn how to make the computer do what you want it to.

What is programming? Programs are a set of instructions for the computer Computers are DUMB Computer only understands binary, or specifically machine code, low-level code Programs are high-level, written for humans – C, C++, Ruby, Java, Perl, LISP… Programs have to be translated for the computer – Compiling vs. interpreting

What is programming? Programs typically must be written for a specific platform or operating system – Operating system: Windows 7, MacOSX, Red Hat – Platform: combination of the hardware architecture and software that runs on it We have several languages we could write in, all of which perform better with a certain purpose in mind

Procedural vs. Object-Oriented Procedural programming is linear: – Functions and procedures are pre-defined – When the program is run, it’s stepped through in a very straightforward manner Object-oriented models the everyday world: – With OOP, we can have a real-world object with attributes and methods – Agent object sends a message, and doesn’t know what will happen – Receiving object has to carry out instructions Code re-use is very important in both! – Crucial to understanding all programming

Programming Steps 1.Define the problem 2.Design the solution 3.Program code 4.Testing 5.Deployment

Programming Steps 1.Define the problem – What are we trying to accomplish? Why is this program being written? 2.Design the solution 3.Program code 4.Testing 5.Deployment

Programming Steps 1.Define the problem 2.Design the solution – What structure do we need? (functions, objects) – What algorithms will we use? – Write pseudocode – Test the algorithm on paper – what inputs does it need? Where will it fail? 3.Program code 4.Testing 5.Deployment

Programming Steps 1.Define the problem 2.Design the solution 3.Program code – Type it up, compile, repeat – Pre-processing: include files, definitionsCompile: turn source code to assembly to machine or object code – Link with library routines – Load in memory 4.Testing 5.Deployment

Programming Steps 1.Define the problem 2.Design the solution 3.Program code 4.Testing – Execute the program: run in the CPU (Central Processing Unit) – Black box testing – White box testing – Unit testing 5.Deployment

Programming Steps 1.Define the problem 2.Design the solution 3.Program code 4.Testing 5.Deployment – Once we’ve tested sufficiently, we can put the code into the real world!

Programming Steps 1.Define the problem 2.Design the solution 3.Program code 4.Testing 5.Deployment – Once we’ve tested sufficiently, we can put the code into the real world! Repeat steps as necessary: code is rarely, if ever, perfect after the first run

What is a program? Learning to program is a little like learning a foreign language. vocabulary: reserved words, or things the compiler or interpreter already understands also includes user-created identifiers, naming things for the compiler or interpreter grammar: syntax rules guiding understanding

What is a program? Tokens – Comments: for humans; tells a reader of the code what it’s supposed to be doing – Keywords: words used by the language; you’re not allowed to redefine these – Identifiers: words you make up to refer to concepts you’ve written into the code (variables, functions) – Literals: explicit references in the code to numbers or strings (known as “hard-coding”) – Symbols: operators or punctuation in the code

What is a program? Written in hierarchical chunks – Preprocessor statements – Comments – Collection of functions… …which are collections of statements …which are collections of tokens.

What is a program? Let’s write one! The problem: average three numbers

Error types Compilation error: – You made a mistake that makes it impossible for the compiler to figure out what you meant! – Identifiable when the compiler complains. Run-time error: – The compiler was successful, but you made a mistake that makes it impossible for the computer to finish running the program! – Identifiable when you get a complaint when running the program. Logic error: – Your program compiles and runs, but your input produces the wrong output! – Identifiable by doing a program trace and figuring out what the program was supposed to spit out. All of these mean it’s time for debugging.

Homework Student survey on Blackboard – fill it out by tomorrow! Written HW #1 and project #1 due Thursday – Will be up on the course website later tonight