a c programming.pdf

8/13/2019 A C Programming.pdf

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Welcome to S.T.T.P. ON

C-PROGRAMMING

Day-1

Introduction to

Organised by CCTEK Sub Center

Govt.Polytechnic Bijapur

By: S.S.Sadat, Lect

Malik Sandal Polytechnic Bijapur


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12/10/2013 S.S.Sadat Lect Malik Sandal PolytechnicBijapur,Mobile No +91 9448179626, E-mail

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Introduction to CProgramming


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Agenda

1.0 Programming Language

2.0 Program Development Steps

3.0 History & Introduction to C 4.0 Basics Environment of C

5.0 Simple C Program

6.0 Characters and Tokens 7.0 Input/output in C


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1.0 Programming Language

A programming language is a formal language

designed to communicate instructions to computer.

A vocabulary and set of grammatical rules for

instructing a computer to perform specific tasks.

Programming languages can be used to create programs thatcontrol the behaviour of a machine and/or to express

algorithms precisely.
http://en.wikipedia.org/wiki/Formal_languagehttp://en.wikipedia.org/wiki/Machine_instructionhttp://en.wikipedia.org/wiki/Computerhttp://www.webopedia.com/TERM/C/computer.htmlhttp://en.wikipedia.org/wiki/Program_(machine)http://en.wikipedia.org/wiki/Algorithmhttp://en.wikipedia.org/wiki/Algorithmhttp://en.wikipedia.org/wiki/Program_(machine)http://www.webopedia.com/TERM/C/computer.htmlhttp://en.wikipedia.org/wiki/Computerhttp://en.wikipedia.org/wiki/Machine_instructionhttp://en.wikipedia.org/wiki/Formal_language


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Types of Language

First

Generation

SecondGeneration

Third

Generation

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First Generation

Machine language

Natural language of a particular computer

Consists of strings of numbers(1s, 0s)

Instruct computer to perform elementary operationsone at a time

Machine dependant

Strings of numbers giving machine specific instructions

The only language the computer can understand

is machine language (binary language).


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Second Generation

Assembly language

English like abbreviations

Translators programs called Assemblers to convert

assembly language programs to machine language.

E.g. add overtime to base pay and store result in gross pay

LOAD BASEPAY

ADD OVERPAY

STORE GROSSPAY


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Fifth Generation

languages used for artificial

intelligence and neural networks


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your program into machine language

(Translators)

Translators are system software used to

convert high-level language program into

machine-language code.

two ways to do this:

Compile the program

Interpretthe program

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Convert

Compiler : Coverts the entire source program at a

time into object code file, and saves it in

secondary storage permanently.

Interpreter : Each statement of source program istranslated into machine code and executed

immediately.

Translation is repeated for every execution of the

source program.

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Machine Language Assembly Language High-Level Language

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entry main,^m

sub12 #12,sp

jsb C$MAIN_ARGS

moveb $CHAR_STRING_CON

pusha1 -8(fp)

pusha1 (r2)

calls #2,SCANF

pusha1 -12(fp)

pusha1 3(r2)

calls #2,SCANF

mull3 -8(fp),-12(fp),-

pusha 6(fp)calls #2,PRINTF

clrl r0

ret

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00000000 00000100 0000000000000000

01011110 00001100 11000010 0000000000000010

11101111 00010110 0000000000000101

11101111 10111110 0000000000001011

11111000 10101101 11011111 0000000000010010

01100010 11011111 0000000000010101

11101111 00000010 11111011 0000000000010111

11110100 10101101 11011111 0000000000011110

00000011 10100010 11011111 0000000000100001

11101111 00000010 11011111 0000000000100100

01111110 11110100 10101101

11111000 10101110 11000101 0000000000101011

00000110 10100010 11111011 000000000011000111101111 00000010 11111011 0000000000110100

01010000 11010100 0000000000111011

00000100 0000000000111101

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#include

int main(void)

{

int n1, n2,product;

printf(Enter two numbers : );

scanf(%d %d,&n1,&n2);

product = n1 * n2;

printf(%d,product);

return 0;

}

A low level language corresponds closely to machinecode so that a single low-level language instruction

translates to a single machine language instruction.

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Programming languages and scripting

languagesALGOL

Ada

AIML

Assembly

AutoHotkey

BASICBatchfile

BCPL

C

C#

C++

COBOL

CPL

D

DarkBASIC

dBASE

FORTRANFoxPro

HDML

HTML

Java

JavaScriptJCL

LISP

Live Script

LOGO

Pascal

Perl

PHP

Pick

Python

PrologRuby

SGML

Smalltalk

SQL

TclTrue BASIC

VHDL

Visual Basic

Visual FoxPro

WML

WHTML

XML

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2.0 Program Development Steps1)Statement of Problem

a) Working with existing system and using properquestionnaire, the problem should be explained

clearly.

b) What inputs are available, outputs are required

and what is needed for creating workable solution

should be understood clearly.

2)Analysis

a) The method of solutions to solve the problem canbe identified.

b) judge that which method gives best results

among different methods of solution.

3)Designing

a) Algorithms and flow charts will be prepared.

b) Keep focus on data, architecture, user interfaces

and program components.4)Implementation

The algorithms and flow charts developed in the

previous steps are converted into actual programs in

the high level languages like C.

4.a)Compilation

Translate the program into machine code. Thisprocess is called as Compilation. Syntax errors are

found quickly at the time of compiling the program.

These errors occur due to the usage of wrong

syntaxes for the statements.

Eg: x=a*y+b

There is a syntax error in this statement, since, each

and every statement in C language ends with a

semicolon (;).

4.b)Execution

The next step is Program execution. In this phase, we

may encounter two types of errors.

Runtime Errors: these errors occur during the

execution of the program and terminates theprogram abnormally.

Logical Errors: these errors occur due to incorrect

usage of the instructions in the program. These

errors are neither detected during compilation or

execution nor cause any stoppage to the program

execution but produces incorrect result

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Algorithms

Step by step procedure designed to perform an operation,

and which (like a map or flowchart) will lead to the

sought result if followed correctly.

Algorithms have a definite beginning and a definite end, and a

finite number of steps.

An algorithm produces the same output information as given

the same input information, and several short algorithms can

be combined to perform complex tasks .

The word algorithm comes from the name of a Persian

author, Abu Jafar Mohammed ibn Musa al Khowarizmi (c. 825

A.D.), who wrote a textbook on mathematics.

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Flow Chart

A flowchart is a type ofdiagram that

represents an algorithm or process, showing

the steps as boxes of various kinds, and their

order by connecting them with arrows.

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Basic Flowchart shapes

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Loops

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Flow chart symbols

Oval Terminal

Parallegram Input/output

Rectangle Process

Document Hard copy

Diamond Decision

Circle Connector

Double sided Rectangle Sub program

Hexagon Iteration

Trapezoid Manual Operation

Cylinder Magnetic Disk Storage

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Area of rectangle

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1. Flowchart for a program to calculate

the area of a square

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Sum and average

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3.0 History & Introduction to C

Evolved from two previous languages BCPL , B

BCPL (Basic Combined Programming Language)

used for writing OS & compilers B used for creating early versions of UNIX OS

Both were typeless languages

C language evolved from B (Dennis Ritchie Bell

labs)

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Introduction to C

Dennis M. Ritchie

C programming language is also a high-level programming languagedeveloped by

Dennis Ritchie at Bell Labs

in 1972from an almost unknown language

named B.

in 1978 the publication of

The C Programming Language by

Kernighan & Ritchie
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"ANSI C"

In 1983, the American National Standards

Institute (ANSI) established a committee to

provide a modern, comprehensive definition

of C. The resulting definition, the ANSIstandard, or "ANSI C", was completed late

1988

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first "portable" language

Cborn in the Computer Science Research Department of Bell Labs

in Murray Hill,

The first major program written in C was theUnix operating system,

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Why use C? Mainly because it produces code that runs nearly

as fast as code written in assembly language.Some examples of the use of C might be: Operating Systems Language Compilers, Embedded systems

Assemblers Text Editors Print Spoolers Device drivers ,Network Drivers Modern Programs Data Bases , graphics and computational geometry Language Interpreters Application programs & Utilities

Mainly because of the portability that writing standard C programs can

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Development with C

Four stages

Editing: Writing the source code by using some editor

Preprocessing or libraries: Already available routines

compiling: translates or converts source to object code for a specific platform

source code -> object code

linking: resolves external references and produces the executable module

Portable programs will run on any machine but..

Note! Program correctness and robustness are most important thanprogram efficiency

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4.0 Basics Environment of C C systems consist of 3 parts

Environment

Language

C Standard Library

Development environment has 6 phases Edit

Pre-processor

Compile

Link Load

Execute

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Basics of C Environment

Editor DiskPhase 1Program edited inEditor and stored

on disk

Preprocessor DiskPhase 2

Preprocessor

program processesthe code

Compiler DiskPhase 3

Creates object code

and stores on disk

Linker DiskPhase 4

Links object code

with libraries and

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Basics of C Environment

LoaderPhase 5

Puts program in

memory

Primary memory

CPUPhase 6

Takes each instruction

and executes it storingnew data values

Primary memory

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5.0 Simple C Program

/* A first C Program*/

#include

void main()

{printf("Hello World \n");

}

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Structure of a C program

#include

void main (void)

{

printf(\nHello World\n);

}

Preprocessor directive (header file)

Program statement

#include #define VALUE 10

int global_var;

void main (void)

{

/* This is the beginning of the program */

int local_var;

local_var = 5;

global_var = local_var + VALUE;

printf (Total sum is: %d\n, global_var); // Print out the result}

} Preprocessordirective

Global variable declarationComments

Local variable declaration

Variable definition

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Simple C Program

Line 1: #include

As part of compilation, the C compiler runs a programcalled the C preprocessor. The preprocessor is able to

add and remove code from your source file.

In this case, the directive #include tells thepreprocessor to include code from the file stdio.h.

This file contains declarations for functions that theprogram needs to use. A declaration for the printffunction is in this file.

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Preprocessor Directives

The first thing to be checked by the compiler. Starts with #.

Tell the compiler about specific options that itneeds to be aware of during compilation.

There are a few compiler directives. But only 2 ofthem will be discussed here.

#include

Tell the compiler to include the file stdio.h during compilation

Anything in the header file is considered a part of the program

#define VALUE 10

Tell the compiler to substitute the word VALUE with 10 duringcompilation

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Simple C Program

Line 2: void main()

This statement declares the main function.

A C program can contain many functions but mustalways have one main function.

A function is a self-contained module of code that canaccomplish some task.

Functions are examined later. The "void" specifies the return type of main. In this

case, nothing is returned to the operating system.

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Simple C Program

Line 3: {

This opening bracket denotes the start of the

program.

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Simple C Program

Line 4: printf("Hello World \n");

Printfis a function from a standard C library that isused to print strings to the standard output, normally

your screen. The compiler links code from these standard libraries

to the code you have written to produce the finalexecutable.

The "\n" is a special format modifier that tells theprintfto put a line feed at the end of the line.

If there were another printfin this program, its stringwould print on the next line.

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Simple C Program

Line 5: }

This closing bracket denotes the end of the

program.

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6.0 Characters and Tokens

Characters are thebasic building blocks

in C program,

equivalent to letters

in English language

Includes every

printable character

on the standard

English language

keyboard except .

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Character Set of C-Language

Numeric digits: 0 - 9

Lowercase/uppercase letters: a - z

and A Z

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Special Symbols : ~ ! @ # $ % ^ & ( ) _ - + = | \ - * + : ; < > , . ? /

White Spaces : space , Horizontal tab, Vertical tab, New Line

Form Feed.


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There are 6 kinds of tokens in C:

Reserved words (keywords)

Identifiers

Constants

String literals Boundaries or Separators or Delimiters

Operators

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Reserved Words

Key words : have a predefined meaning and these

meanings cannot be changed.

Have special meaning to the compiler, cannot be

used as identifiers in program. Should be typed in lowercase.

Example: const, double, int, main, void, while, for,

else (etc..)

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Example

Keywords

auto double int struct

break else long switch

case enum register typedef

char extern return union

const float short unsigned

continue for signed void

default goto sizeof volatile

do if static while

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Primary Data Types

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Data

Types

int float Double char


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Basic Data Types

basic data types:

int (used to declare numeric program variables of

integer type)

char (used to declare character variable)

double (used to declare floating point variable)

In addition, there are float, void, short, long, etc.

Declaration: specifies the type of a variable.

Example: int local_var;

Definition: assigning a value to the declaredvariable.

Example: local_var = 5;

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Constants(Literals)

Fixed values that do not change during execution

of a program types of constants:

Boolean constants : 0 ( false) and 1 (true)

Integer constants

Positive or negative whole numbers with no fractional part

Example:

const int MAX_NUM = 10;

const int MIN_NUM = -90;

Floating-point constants Positive or negative decimal numbers with an integer part, a

decimal point and a fractional part

Example:

const double VAL = 0.5877e2; (stands for 0.5877 x 102)

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Character constants

A character enclosed in a single quotation mark

Example: const char letter = n;

const char number = 1;

printf(%c, S);

Output would be: S

Enumeration Values are given as a list

Example:

enum Language {

Malay,

English,

Arabic

;

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String Literals

A sequence of any number of characters

surrounded by double quotation marks.

Example:

REFORMASI

My name is Salman

Example of usage in C program:

printf(My room number is BN-1-012\n);

Output: My room number is BN-1-012

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String Constants : Hello world , Have a nice day!

Complex Constants : real part + imaginary part * I ex : 12.3 + 3.45 * I


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Identifiers(variables)

Words used to represent certain program entities(program variables, function names, etc).

Example:

int my_name;

my_name is an identifier used as a program variable

void CalculateTotal(int value)

CalculateTotal is an identifier used as a function name

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Variables in C

Variables contain values that must be kept duringthe completion of a program (storage) for futureuse.

In C, a variable MUST be declared before it can beused.

Variables can be declared at the start of any blockcode, but most are found at the start of each

function (main inclusive) Local variables are created when the function is

called and destroyed on return from that

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Constructing variable names

Rules for define identifiers :a) First character must be alphabetic

character or under scoreb) Second character onwards alphabetic

character of digit or under score.c) First 63 characters of an identifier aresignificant.

d) Cannot duplicate a key word.

e) May not have a space or any other specialsymbol except under score.f) C language is Case-sensitive.

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How to declare a variable?

a declaration begins with the type, followed

by the name of the variable:

int x; //declares an integer variable x

More than one variable can be assignedand a

starting value can be given:

float x,y=-2.5,tab[20];

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A variable can be declared globally or locally.

A globally declared variable can be accessed from

all parts of the program.

A locally declared variable can only be accessed

from inside the function in which the variable isdeclared.

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Punctuators (separators)

Symbols used to separate different parts of the Cprogram.

These punctuators include:

* + ( ) - , ; : #

Usage example:

void main (void)

{

int num = 10;

printf (%i, num);

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Delimiters : Language Pattern of c-languageuses special kind of symbols

: (colon, used for labels) ; (semicolonterminates statement ) ( ) parameter list[ ] ( array declaration and subscript ), { }( block statement )

# ( hash for preprocessor directive ) ,

(comma variable separator )


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Operators

Tokens that result in some kind of computation oraction when applied to variables or or other

elements in an expression.

Example of operators:

* + = - /

Usage example:

result = total1 + total2;

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Comments

Explanations or annotations that are included in aprogram for documentation and clarification

purpose.

Completely ignored by the compiler duringcompilation and have no effect on program

execution.

Starts with / and ends with /

Some compiler support comments starting with//

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statement

A specification of an action to be taken by the

computer as the program executes.

In the previous example, there are 2 lines following

variable declaration and variable definition thatterminate with semicolon ;.

global_var = local_var + VALUE;

printf(Total sum is: %d\n, global_var);

Each line is a statement.

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Input/output statement

Used the read the data value

scanf(%d %d%d,&a, &b &c); input function

Output used to print the result

Printf(The sum=%d, sum) ; output function

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7.0 Input/output in C

C language consists of input and output

statement in the form of input functions to

read the data to be processed and output

function to print the result. A C program consists of one or more functions

that contain a group of statements which

perform a specific task.

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Basic Functions

A C program must at least have one function: thefunction main.

We can create our own function or use the

functions that has been created in the library, in

which case we have to include the appropriateheader file (example: stdio.h).

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pre-defined in the header file stdio h


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pre-defined in the header file stdio.h

These functions are: printf()

scanf()

getchar() & putchar()

In addition to those functions, we will also learn

about Format Specifier and Escape Sequence

which are used with printf() and scanf().

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printf()


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printf()

Used to send data to the standard output (usually

the monitor) to be printed according to specific

format.

General format:

printf(control string, variables);

Control string is a combination of text, formatspecifier and escape sequence.

Example:

printf(Thank you); printf(Total sum is: %d\n, global_var);

%d is a format specifier

\n is an escape sequence

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Conversion Specifiers (Format Specifier)


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p ( p )

Code Format

%a Hexa decimal output in the form of 0xh.hhhhp+d(C99 only)

%s String of characters (until null zero is reached )

%c Character%d Decimal integer

%f Floating-point numbers

%e Exponential notation floating-point numbers

%g Use the shorter of %f or %e

%u Unsigned integer

%o Octal integer%x Hexadecimal integer

%i Signed decimal integer

%p Display a pointer

%n The associated argument must be a pointer to integer, This sepecifier causesthe number of characters written in to be stored in that integer.

%hd short integer%ld long integer

%lf long double

%% Prints a percent sign (%)

Tells the printf() function the format of the output to be printed put.

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Conversion Specifiers


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Conversion Specifiers

(Format Specifier)

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Code Format %s String of characters (until null zero is reached )

%c Character

%d Decimal integer

%f Floating-point numbers

%e Exponential notation floating-point numbers

%lf long double

%% Prints a percent sign (%)

Commonly used specifiers


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Escape Sequence (commonly used)

\n new line

\t tab

\r carriage return

\a alert

\\ backslash

\ double quote

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Escape sequence is used in the printf() function to do something to

the output.

scanf()


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scanf()

Read data from the standard input device (usuallykeyboard) and store it in a variable.

General format:

scanf(Control string, &variable);

The general format is pretty much the same asprintf() except that it passes the address of thevariable (notice the & sign) instead of the variableitself to the second function argument.

Example:int age;

printf(Enter your age: );

scanf %d, &a e ;

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getchar() and putchar()

getchar() - read a character from standard input putchar() - write a character to standard output

Example:

#include

void main(void)

{

char my_char;

printf(Please type a character: );

my_char = getchar();printf(\nYou have typed this character: );

putchar(my_char);

}

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Data Types ( pre defined )


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Type Typical Size in Bits Minimal Range

char 8 127 to 127

unsigned char 8 0 to 255

signed char 8 127 to 127

int 16 or 32 32,767 to 32,767

unsigned int 16 or 32 0 to 65,535

signed int 16 or 32 Same as int

short int 16 32,767 to 32,767

unsigned short int 16 0 to 65,535signed short int 16 Same as short int

long int 32 2,147,483,647 to 2,147,483,647

long long int 64 (263) to 263 1 (Added by C99)

signed long int 32 Same as long int

unsigned long int 32 0 to 4,294,967,295

unsigned long long int 64 264 1 (Added by C99)

float 32 3.4e-38 to 3.4e+38

double 64 1.7e-308 to 1.7e+308

long double 80 3.4e-4932 to 1.1e+4932

void -- data type that not return any value

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8.0 Arithmetic in C

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C op era tion Arithmeticoperator

Algeb raicexpression

C exp ression

Addition + f + 7 f + 7

Subtraction - pc p - c

Multiplication * bm b * mDivision / x / y x / y

Modulus % r mod s r % s


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Precedence order

Highest to lowest

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Operator(s) Operation(s) Order of evaluation (precedence)

() Parentheses Evaluated first. If the parentheses are nested, the

expression in the innermost pair is evaluated first. If thereare several pairs of parentheses on the same level (i.e.,

not nested), they are evaluated left to right.

*, /, or% Multiplication,Divi

sion, ModulusEvaluated second. If there are several, they are

evaluated left to right.

+or- Addition

Subtraction

Evaluated last. If there are several, they are

evaluated left to right.


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ExampleAlgebra:

z = pr%q+w/x-y

C:

z = p * r % q + w / x y ;

Precedence:

1 2 4 3 5

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ExampleAlgebra:

a(b+c)+ c(d+e)

C:

a * ( b + c ) + c * ( d + e ) ;

Precedence:

5

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1 2

3 4

k


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Decision Making

Checking falsity or truth of a statement

Equality operators have lower precedence

than relational operators

Relational operators have same precedence

Both associate from left to right

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k


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Decision Making

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Standard algebraic

equality operator orrelational operator

C equality or

relationaloperator

Example of C

condition

Meaning of C

condition

Equality Operators

= == x == y xis equal to y

not = != x != y xis not equal to y

Relational Operators

> > x > y xis greater than y

< = >= x >= y xis greater than or

equal to y


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Assignment operators

Used to assign the RHS value to LHS variable

= a=10; b=5; sum=a+b;

+= a+=b; is equivalent to a=a+b;

-= c-=d: c=c-d;

*= p*=d; p=p*d;

/= d/=d; d=d/s;

%= i%=j; i=i%j;

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height = 8; length = 12; width = 10;

volume = height * length * width;

/* volume is now 960 */

I / d


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Increment/ decrement operators

++ ++a prefix increment (++a)

++ a++ postfix increment (a++)

-- --a prefix decrement(- -a)

-- a-- postfix decrement (a- -)

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I / d


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Increment/ decrement operatorsmain(){

int c;c = 5;printf(%d\n, c);printf(%d\n, c++);printf(%d\n\n, c);

c = 5;printf(%d\n, c);printf(%d\n, ++c);printf(%d\n, c);

return 0;}

5

5

6

5

6

6

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/* prefix operators */


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/ prefix operators /

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#include int main() {

int a = 7, b = 12, c;

c = b * (++a) + 5 * (++a);

printf( a = %d, a); printf(\n b = %d,b);

printf(\n c = %d,c);

}

Output:

a = 9

b = 12

c = 153 ( 12 * 9 + 5 * 9)


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/* prefix and postfix operators */

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int a = 7, b = 12, c;

c = b * (a++) + 5 * (++a);



}

Output:

a = 9

b = 12

c = 136 ( 12 * 8 + 5 * 8)

/* fi d tfi t */


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/* prefix and postfix operators */

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int a = 7, b = 12, c;

c = b * (a++) + 5 * (++a);



}

Output:

a = 9

b = 12

c = 136 ( 12 * 8 + 5 * 8)


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