CS 251 C Programming for Engineers Spring 2016 Instructor: Dick Lang

Goals We will learn –Read: Understand programs written in C language –Write: Design and implement programs using C language –Compile: Use compiler to convert C code into executable file in the UNIX environment. –Execute: Run corresponding code to get results –Debug: Identify and fix syntax and semantic errors in C code. –Simple numerical programming techniques –Basic data structure construction and operations (pointers!) Appropriate for –Technically oriented people with little or no programming experience, but with a strong mathematics background

View of Computers From a programmer’s viewpoint –Computers are tools –A computer program (hopefully) turns raw data into meaningful information –A program is the driving force behind any job that any computer does A program is a list of detailed instructions These instructions are written in a particular programming language

Your Mindset… From an engineer’s point of view: –A computer/program may control a mechanism or process –A computer/program may analyze data and aid in drawing conclusions or decision-making –A computer can model a mechanism or circuit in advance of fabricating it Embedded computers are components of most electro-mechanical systems and products

Available Programming Languages Machine Languages Assembly Languages High-level Languages –C/C++ –COBOL (obsolete) –Pascal (academic) –Fortran (nearing obsolescence) –Java –Python –etc…

Machine Languages System of instructions and data directly understandable by a computer's central processing unit (i.e. hardware). Example: Every CPU model has its own machine code, or instruction set, although there is considerable overlap between some

Assembly Languages Human-readable notation for the machine language that a specific computer architecture uses, representing elementary computer operations (translated via assemblers) Example: load hourlyRate, r1 mul workHours, r1 store salary, r1 Even into the 1990s, the majority of console video games were written in assembly language.

High-level Languages Higher level of abstraction from machine language –Codes “similar” to everyday English Use mathematical expressions (translated via compilers) –Example: salary = hourlyRate * workHours Make complex programming simpler => make programming more productive & reliable

Why Program using C Initial development occurred at Bell Labs in early 70’s by Ritchie, as part of Unix OS development General-purpose computer programming language –high-level assembly –Simplicity and efficiency of the code Most widely used compiled programming language –Commonly used for writing system software –Widely used for writing applications –Hardware independent (portable, mostly) –Great influence on many other popular languages (C++, Java)

Outline of the Course – I Introductory information C program structure Basic data types and variables declaration Arithmetic expressions and operators Control statements. –Conditional statements –The while loop –The do while loop –The for loop –The if else statement –The switch statement –The break statement –The continue statement

Outline of the Course – II Formatted Input and Output Arrays and Strings Functions –Declarations –Calling Pointers Struct(ures) Preprocessor * Advanced Material –Debug using gdb and/or Visual Studio –Binary Trees –Link Lists –Recursive Functions * may be adjusted according to time and interests of students

History- I ENIAC I (Electrical Numerical Integrator And Calculator) John Mauchly and J Presper Eckert 500,000 dollars (in 1946) –17,468 vacuum tubes –70,000 resistors –10,000 capacitors, etc –800 square feet floor space –30 tons –160 kilowatts of electrical power The ENIAC 1946

History- II First home computer –Mark-8 Altair –IBM 5100 Computers 1974/1975 Altair –8080 CPU –256 Byte RAM card –$400 –The consumer needs to put them together, make it work and write any needed software. –Paul Allen and Bill Gates develop BASIC for the Altair 8800 Mark-8 Altair

History- V Personal computer –Apple II in 1977 –IBM PC in 1981 –Apple Macintosh in 1984 –Microsoft Windows 1.0 ships in November, 1985 original IBM PC 1981

Operating System What is an OS? –A program that allows you to interact with the computer -- all of the software and hardware With a command-line operating system (e.g., DOS) With a graphical user interface (GUI) operating system (e.g., Windows) Two major classes of operating systems –Windows Nice interface ?, easy to learn ? –Unix reliable timesharing operating system Embedded computers use “real-time” OS’s which do not require disks…

Why choose UNIX Powerful –Multi-user operating system –Good programming tools Most heavy-duty database management systems started out on Unix Flexible –Thousands of tools that can be combined and recombined. Reliable –Unix is hard to crash. Simple things are simple in Unix…

Your First Program #include int main() { printf("Hello World\n"); return 0; } Preprocessor: interact with input/output of your computer You will see this at the beginning of nearly all programs Tells computer to load file named allows standard input/output operations

Your First Program #include int main() { printf("Hello World\n"); return 0; } Start point of the program Preprocessor: interact with input/output of your computer C programs contain one or more functions, exactly one of which must be main int means that the function main will "return" an integer value

Your First Program #include int main() { printf("Hello World\n"); return 0; } Start point of the program Preprocessor: interact with input/output of your computer Start and finish of function

Your First Program #include int main() { printf("Hello World\n"); return 0; } Printing a line of Text Start point of the program Preprocessor: interact with input/output of your computer Start and finish of function

Your First Program #include int main() { printf("Hello World\n"); return 0; } Printing a line of Text Start point of the program Preprocessor: interact with input/output of your computer Start and finish of function New line character

Your First Program #include int main() { printf("Hello World\n"); return 0; } Printing a line of Text Start point of the program Preprocessor: interact with input/output of your computer Start and finish of function Finish and return value 0 A way to exit a function It means that the program terminated normally in this case

Comments for programs Why comments are needed –Good habit –Readable to others –Remind yourself How to comment –/* … */ –// … Examples

Compiler What is compiler –A computer program (or set of programs) that translates text written in a computer language ( the source code) into another computer language (usually, an executable file) Why we need a compiler Available C compiler in UNIX system: gcc gcc sourcefile.c –o exefile

Procedure This is your C program. Type the code in any standard text editor, and save it as helloworld.c #include int main() { printf("Hello World\n"); return 0; } helloworld.c C-compiler Type gcc helloworld.c –o helloworld to compile helloworld.c into helloworld using the gcc compiler helloworld The gcc compiler generates the corresponding executable code named helloworld. The computer can execute this machine readable code if you type./helloworld