C Programming Day 1 - PowerPoint Presentation

Slide1

C Programming Day 1 based upon Practical C Programming by Steve Oualline

CS550

Operating SystemsSlide2

About C C is a structural (also called imperative) programming languageEach program is viewed as a group of operations or actions

Programs may be modularized

statements

--------

------

----Slide3

Programming processSpecify a task (design)Find an algorithm to complete the task

Write code

Test your code

Repeat from appropriate pointSlide4

Preprocessor Directives

Like import statements in Java these allow you to include code that already exists

#include <filename>

#include <

stdio.h

> //Standard input/output

#include "

myheader.h

" //homemade header file

/

/The

printf

function comes from

stdio.h

printf

("Hi my name is...\n");Slide5

Preprocessor DirectivesYou can also use preprocessor directives to create constants or macros

#define // <-- use to create constants or a macro

#define PI 3.14

//Never use PI 3.14; <-- semicolons should not be used when defining

//a constantSlide6

CompilationCompiler Translates C code to machine code

Linker

takes object code (intermediate code) and joins it togetherSlide7

Compilation At $ prompt

gcc

prog1.c

–

std

=c99

-o prog1

.c file - source code

-

std

=

c99

– Use

C99 standard

-o

- output to a specific file

prog1

- executable file

Without an executable specified with –o,

a.out

is the executableSlide8

Comments and a Simple C Program

/* a multiline comment */

//a one line comment

#include <

stdio.h

>

int

main(

int

argc

, char **

argv

)

{

printf

("Hello, world!\n"):

return 0;

}Slide9

Primitive Variable DeclarationsVariable declarations similar to Java

i

nt

centimeters, meters, kilometers;

d

ouble watts;

c

har

y_or_n

= ‘y’;Slide10

BlocksBlocks similar to Java

//A BLOCK

{

declarations

statements

}Slide11

AssignmentAssignment statements comparable to Java

int

a;

a = 1 + 2 * 5;

result --> a = 11

Results of RHS stored in LHSSlide12

printfPrint statements may be performed using

printf

similar to, but not exactly the same as, Java

Format:

printf

(control string, variable list);

variable list -> variable | variable listSlide13

Example Program#include <

stdio.h

>

int

main(

int

argc

, char **

argv

)

{

int

meters = 8;

printf

(“%d meters\n”, meters);

}

Result:

8 metersSlide14

Another Example#include <

stdio.h

>

int

main(

int

argc

, char **

argv

)

{

int

kilometers = 10, meters = 7, centimeters = 8;

printf

(“%d %d %d\n”, kilometers, meters, centimeters);

}

Result:

10 7 8

What if we reorder the variable list?Slide15

Common Conversion Specifications%d

-

int

(often 4 bytes)

%lf

-

double

(often 8 bytes)

%c

- ASCII character or

char

(often 1 byte)

%f

-

float

(often 4 bytes)

%s

- string (

NULL

terminated)Slide16

Escape CodesUsed to represent characters that aren't readily visible in strings

\n

new line (in

L

inux this represents return)

\r

return (in Windows

\n\r

represents return)

\t

tab

\'

single quote

\"

double quote

\\

backslashSlide17

Reserved wordssigned, unsigned,

struct

union, char,

int

, float, double

while, for, if, do, short

long, static, auto, extern

register

Remember that C is case sensitive!Slide18

Arithmetic Expressions in C* multiplication

/ division

% modulus (remainder)

+ addition

- subtractionSlide19

Order of Operations1. ()

2. unary negation

3. * / %

4. + -

Example: 2 + 3 % 7

3 % 7 = 3

2 + 3 = 5Slide20

Example Program

#include <

stdio.h

>

int

main(

int

argc

, char **

argv

)

{

int

kilometers, meters, centimeters;

kilometers = 4;

meters = 1000*kilometers;

centimeters = 100*meters;

printf

("The length of a bridge :\n");

printf

("%

s%s

\n", "The length", " of a bridge");

printf

(”The length in different units:\n");

printf

("%d kilometers\n", kilometers);

printf

("%d meters\n", meters);

printf

("%d centimeters\n", centimeters);

return 0;

}