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Software ProjectInstructor: Roded Sharan, [email protected]: Dana Silverbush

Course materials: virtual.tau.ac.il

http://www.cs.tau.ac.il/~roded/courses/soft-project12b.html

A Book on C - ABCKelley/Pohl

Addison-WesleyFourth Edition

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Course Structure

The C programming language: 8-9 classes

including 2 exercises (5%+10%; mandatory) and a

final exam (30%).

Large project (55%): in pairs,

2 classes will be devoted to its presentation;

includes interfacing an integer linear programming

library (CPLEX).

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The C programming language

B, initial versions of UNIX, 1970

C, Deniss Ritchie, Bell Labs, 1972;

overcomes Bs typeless representation;used for developing UNIX.

Early 80s - traditional C

1990 the ANSI-C standard

C++ and Java

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Why C ?

C is compact: few reserved words, tersecommands, powerful set of operators.

C is efficient: direct memory management, some

operators directly modify machine registers,manipulation of memory addresses.

C is modular and typed.

C is the native language ofUNIX.

Basis of C++ (and Java).

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C is also beautifulmain(){char q=34,n=10,*a="main() {char q=34,n=10,*a=% c%s%c;printf(a,q,a,q,n);}%c";printf(a,q,a,q,n);}

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C vs. Java

Java was developed based on C and inherited

most of its syntax.

Main difference: C is procedural and not object-oriented. Thus, no classes/interfaces; methods are

called functions and do not belong to any object.

Similar primitive types as in Java, but no booleanand string types; other differences.

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C vs. Java (cont.)

Pointers instead of references. Allow direct access to

memory and dereferencing (but less elegant).

No garbage collection need to manage memoryexplicitly.

Preprocessor.

Compilation to machine code faster but some

platform dependency; java is processed via an

interpreter (JVM).

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C Topics

Lexical elements (Ch. 2) Fundamental data types (Ch. 3)

Flow of control (Ch. 4)

Functions (Ch. 5); Runtime environment

Arrays, pointers and strings (Ch. 6); Dynamic matrix

allocation (Ch. 12.6)

Bitwise operators (Ch. 7)

Preprocessor (Ch. 8)

Structures (Ch. 9)

Linked lists (Ch. 10)

Input/output and files (Ch. 11)

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Programming Environment

Unix

Make

CPLEX

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Operating System

Operating system:

Manages the available hardware (CPU, memory)

and software (editors, development tools) resources.

Provides interface for using them by multiple users.

Users AUI API OS kernel Hardware

Shell: command-line interpreter to interface the OS.

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The Unix OS

Unix: multi-user, multi-process OS; open source.

History:

1969 Initial version by Thompson & Ritchie at Bell

Labs (assembly and later B). 70s Rewritten in C.

80s System-V (AT&T) and BSD (Berkeley)

versions.

90s Linux by Linus Torvalds.

For basic introduction and commands see web-page.

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Project

Task: Clustering via integer linear programming (ILP)

Goals:

Large scale programming

Efficient computation

Real world application (biological networks) Interfacing an external library (CPLEX)

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Lexical Elements

(chapter 2)

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The C System

edit hello.c compile hello.o link hello

C

Standard

library

PreprocessorLexical analysis

Syntax analysis

Semantic analysis

Keywords

Identifiers

Constants

Operators

Punctuation

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Keywords

Reserved words with a strict meaning

C does a lot with relatively few keywords.

auto do goto signed unsigned break

double if sizeof void case else

int static volatile char enum long

struct while const extern register switch

continue float return typedef default for

short union

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Identifiers

A token composed of a sequence of letters

tax = price * tax_rate

First character cannot be a digit!!5a_cse is not legal

Case sensitive

CSE_5a is different from cse_5a

Some identifiers are already taken: keywords.

Choose names that are meaningful (cse_5a is not a good example!!)

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Comments

Arbitrary strings placed between the delimiters/* and */.

/*

* A comment can be written in this fashion

* to set it off from the surrounding code.*/

For single line comments (do not follow the ANSI standard):

// This is a comment in c++

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Fundamental

data typesChapter 3 in ABC

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Integral (signed or unsigned)

char

short

int

longFloating point types

float

double

Fundamental Data Types

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Integral Types:

char signed char unsigned char

short int long

usigned short unsigned unsigned long

Floating Types:

float double long double

Declaration is important for:

Memory allocation

Interpreting the number correctly within expressions.

Fundamental Data Types

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Constants

a, x, 0, &, \nchar

1, 0, -54, 4234567int

0l, 123l, 7766llong

0u, 23u, 3000000000uunsigned

1.2f, .2f, 1.f, 3.14159ffloat

1.0, -3.1412, 1.2e-2double

1.0l, 2.4433llong double

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character: 'a' 'b' 'c' ... 'z'

integer value: 97 98 99 ... 112

character: '0' '1' '2' ... '9'

integer value: 48 49 50 ... 57

character: '&' '*' '+'

integer value: 38 42 43

Some Character Constants

and their Integer Values

The character 0

has a value of 48

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and their Integer Values

char c = 'a';

printf("%c", c);

printf("%d", c);

printf("%c%c%c", c, c+1, c+2);

a is printed

97 is printed

abc is printed

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and their Integer Valuescharacter: 'A' 'B' 'C' ... 'Z'

integer value: 65 66 67 ... 90

char c = 0;

int i = 0;

for ( i = 'a'; i

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Representation

Binary valuevalueType

vvvv vvvvunsigned char

0000 00000unsigned char




svvv vvvv(2-complement)signed char

1111 1111-1signed char

1000 0000-128signed char

svvv vvvv vvvv vvvv vvvv vvvv vvvv vvvvsigned int

v means valuemeans sign[uint-max.c]

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Decimal, Hexadecimal, Octal[conversions.c]

#include

int main(void)

{

printf( %d %x %o\n, 19, 19, 19 );printf( %d %x %o\n, 0x1c, 0x1c, 0x1c);

printf( %d %x %o\n, 017, 017, 017);

printf( %d\n, 11 + 0x11 + 011);

printf( %x\n, 2097151);

printf( %d\n, 0x1FfFFf);

return 0;

}

19 13 23

28 1c 34

15 f 17

37

1fffff

2097151

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Float Representation

Decimal: int.frac*10exp

Binary: 1.frac*2exp

seee eeee sfff ffff ffff ffff ffff ffff

What is the representation of 0.5 ?

0.5+2100 ? [precision.c]

exp+127

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Sizeof

sizeof(char) == 1

sizeof(short)

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compute the size of some

fundamental types[size-of-type.c] on nova":

The size of some fundamental types is computed.

char: 1 byteshort: 2 bytes

int: 4 bytes

long: 8 bytes

unsigned: 4 bytes

float: 4 bytes

double: 8 bytes

long double: 16 bytes

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The usual arithmetic conversion (promotion)If eitheroperand is of type long double, double, floatorunsigned long, the

other operand isconvertedto long double, double, floatorunsigned longappropriately.

Otherwise, the "integral promotions" are performed on both operands

(char/short => int), and the following rules are applied:

If one operand has type long and the other operand has type unsigned then

one of two possibilities occurs:

If a longcan represent all the values of an unsigned, then the operand

of type unsigned isconvertedto long.

If a longcannot represent all the values of an unsigned, thenboth

operands areconvertedto unsigned long.

Otherwise, if either operand is of type long, the other operand isconverted

to long.

Otherwise, if either operand is of type unsigned, the other operand is

convertedto unsigned.

Otherwise, both operands have type int.

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Expressions and Types

char c; short s; int i; unsigned u;

unsigned long ul; float f; double d; long double ld;

Expression Type Expression Type

c s / i int u * 7 i unsigned

u * 2.0 i double f * 7 i float

c + 3 int 7 * s * ul unsigned long

c + 5.0 double ld + c long double

d + s double u ul unsigned long

2 * i / l long u - l system

dependent

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Cast

double d = 3.3;

int i = 0;

unsigned ui = 0;

i = (int)d;

d = (double)i / 2;

ui = (unsigned)i;

i == 3d == 1.5

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