C Intro Class1

8/2/2019 C Intro Class1

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KGISL ITECH 1

KGiSL- iTech


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a language designed for programming computers

is an artificial language designed to expresscomputations that can be performed by a machine,particularly a computer.

a series of instructions written by a programmeraccording to a given set of rules or conventions(syntax ).

is a notation for writing programs. All PL language can be divided into three categories

Problem Oriented or High Level Languages

Machine Oriented or Low Level Languages

Middle Level Language2


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Machine languageNatural language of a particular computer

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

Instruct computer to perform elementary operationsone at a time

Machine dependant

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Assembly Language

English like abbreviations

Translators programs called Assemblers to

convert assembly language programs to machinelanguage.

E.g. add overtime to base pay and store result ingross pay

LOAD BASEPAY

ADD OVERPAY

STORE GROSSPAY 4


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High-level languages

To speed up programming even further Singlestatements for accomplishing substantial tasks

Translator programs called Compilers toconvert high-level programs into machinelanguage

E.g. add overtime to base pay and store result ingross pay

grossPay = basePay + overtimePay

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Procedural Programming Languages

every program comes with a starting phase, a list of tasksand operations, and an ending stage. made up ofprocedures, subroutines, or methods.Fortran, Basic

Structured Programming Languages

requires that programmers break program structure into smallpieces of code.

associated with a "top-down"approach to design.C, Pascal

Object-Oriented Programming Languages requires the designer to specify the data structures as well as the

types of operations to be applied on those data structures. a program thus becomes a collection of cooperating objects,

rather than a list of instructions.C++, Java, Python

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s A language written by Brian Kernighan and Dennis

Ritchie atBell Laboratories.

s C is a general-purpose computer programming languagedeveloped in 1972.

s A Programming language (PL) C is a set of instructionsused to communicate with the computer

s The set of instruction written in a PL is known asprogram

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Evolved from two previous languages BCPL , B

BCPL (Basic Combined Programming

Language) used for writing OS & compilers

B used for creating early versions ofUNIXOS

Both were typeless languages

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C provides:

xEfficiency, high performance and high quality s/w

x flexibility and power

xmany high-level and low-level operations middle level

xStability and small size code

xProvide functionality through rich set of functionlibraries

xGateway for other professional languages likeC C++ Java

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C is used:

xSystem software Compilers, Editors, embeddedsystems

x

data compression, graphics and computationalgeometry, utility programs

xdatabases, operating systems, device drivers,system level routines

xAlso used in application programs

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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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Editor DiskPhase 1Program edited inEditor and stored

on disk

Preprocessor DiskPhase 2

Preprocessor

program processesthe code

CompilerDisk

Phase 3

Creates object code

and stores on disk

Linker DiskPhase 4

Links object code

with libraries and

stores on disk

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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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Four stages

Editing:Writing the source code by using some IDE or editor

Preprocessing or libraries: Already available routines

compiling: translates or converts source to object code for aspecific platform source code -> object code

linking: resolves external references and produces the

executable module

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Include files

Function subprogram

Main function

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Global variable and

function declaration


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/* A first C Program*/

#include

voidmain()

{

printf(Learning C Programming is

easy \n");}

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Line 1: #include

As part of compilation, the C compiler runs a programcalled the C preprocessor. The preprocessor is able toadd and remove code from your source file.

In this case, the directive #includetells the preprocessorto include code from the filestdio.h.

This file contains declarations for functions that theprogram needs to use. A declaration for theprintf()

function is in this file.

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Line 2: void main() This statement declares the main function.

A C program can contain many functions but must alwayshave one main function.

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

Functions are examined later.

The "void"specifies the returntypeof main. In this case,nothing is returned to the operating system.

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Line 3: {

This opening bracket denotes thestartof theprogram.

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Line 4: printf(Learning C Programming is easy\n");

printf() is a function from a standard C library that isused to print strings to the standard output, normally yourscreen.

The compiler links code from thesestandard libraries tothe code you have written to produce the final executable.

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

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

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Line 5: }

This closing bracket denotes the endof theprogram.

Note

s C is a Case Sensitive

s All C statements must be terminated by a semi-colon ( ; )

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Comment should be enclosed between /* */

Single Line Comment is //

It is used to increase the readability of the

program.

Any number of comments can be given at anyplace in the program.

Comment cannot be nested.

It can be split over more than one line

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\n new line \t tab \r carriage return

\a alert \\ backslash \ double quote \? Question Mark \ Quotation Mark \0 Null

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Alphabets

DigitsSpecial-symbols

Constants

VariablesKeywords

Instruction Program

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A character denotes any alphabet, digit orspecial symbol used to representinformation.

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The alphabets, numbers and specialsymbolwhen properly combined form constants,variables and keywords

A constant is a quantity that doesntchange

A variable is a name given to the location inmemory where the constant is stored

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C constants can be divided into two majorcategories Primary Constants

Secondary Constants

C Constants

Primary Constants Secondary constants

Integer Constant

Real Constant

Character Constant

Array, PointerStructure, Union

Enum

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An integer constant must have at least onedigit

It must not have a decimal point

It could be either positive or negative If no sign precedes an integer constant, it isassumed to be positive ex., 123, -321, +78

No commas or blanks are allowed within aninteger constant


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Real constants (RC) must have at leastone digit

It must have a decimal point

It could be eitherpositive or negative

Defaultsign ispositive

No commas or blankare allowed within a RC

Ex., 0.0083, -0.75, +247.0

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A Single character constant is either a singlealphabet, a single digit or a single specialsymbol enclosed within single quotes

The maximum length of a character constantcan be 1 character

Eg a, 1, 5, = (Valid)asd, 12 (Invalid)

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It is a sequence of characters enclosed indouble quotes

Characters may be letters, numbers, specialcharacters enclosed in double quotes.

Eg., Hello! 1987 ?...! X

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Identifiers are names given to variousprogram elements, such as variables,functions and arrays

A variable name is any combination ofalphabets, digits or underscores

The first character in the variable name mustbe an alphabet

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Keywords are the reservedwords

They cannotbe used as variable names.

There are only 32 keywords available in c

auto double if static do

break else int struct goto

case enum long switch signed

char extern near typedef while

const float register union defaultcontinue far return unsigned for

short void

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There are basically four types of instructionsin C

Type declaration instruction

Eg: int sum;float ave;char name,code;

Input/Output instruction Eg: scanf(),

printf()

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Arithmetic instructionEg :

x = sum +2;

Control instruction

Eg :

while do statement

for statementif statement

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C Supports several different types of data, each of which

may be represented differentlywithin the computersmemory.

Basic data types are listed below:

Data Type Description Typical Memory

int integer quantity 2 bytes

char single character 1 bytes

float floating point number 4 bytes

double double-precisionfloating point number 8 bytes

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A variable is a data name that used to store a data value

A variable may take different values at different times duringexecution

A variable name should be meaningful

Ex: Average

Total

Height

1.They must begin with a letter. Some system allows _ as thefirst character.

2.ANSI standard recognizes a length of 31 characters.

3.Length should not be normally more than 8 characters.4.Upper case and lower case are significant.

5.It should not be a keyword.

6.White space is not allowed.

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ValidJohn Value X1 ph_value

mark

Invalid 123

% 25th (area) group 1

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Declaration does two things It tells the compilers what the variable name is It specifies what type of data it holds

Declaration of must be done before they areusedin the program

Syntax : ;

Eg:int count;int num,total;double ratio;

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auto local variable declared within a function

static local variable which exist and retain value evenafter control is transferred to calling function

extern Global variable known to all function

register Local Variable which is stored in the register

static and external variables are automatically initializedto zero

Automatic (auto) variables contains undefined valuescalled garbage unless they are initialized.

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Initialization Syntax: =

Eg:int num = 5;

Values can be assigned using theassignment operator = Eg:int num;

num = 5;

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An operator is a symbol(+,-,*,/) thatdirects the computer to perform certainmathematical or logical manipulations and

is usually used to manipulate data andvariables.

Ex: a + b

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1. Arithmetic operators2. Relational operators

3. Logical operators

4. Assignment operators5. Increment and decrement operators

6. Conditional operators

7. Bitwise operators

8. Special operators

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C operation Algebraic C

Addition(+) f+7 f+7

Subtraction (-) p-c p-c

Multiplication(*) bm b*m

Division(/) x/y, x , x y x/y

Modulus(%) r mod s r%s

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Operators in expressions contained within pairs ofparentheses are evaluated first. Parentheses

are said to be at the "highest level ofprecedence."

((a + b) + c) Multiplication, division and modulus operations are

applied next. If an expression contains several

multiplication, division and modulus operations,operators are applied from left to right.Multiplication, division and modulus are said to beon the same level of precedence.

Addition and subtraction operations are appliedlast. If an expression contains several addition andsubtraction operations, operators are applied fromleft to right. Addition and subtraction also have thesame level of precedence.

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Highest to lowest

()

*, /, %

+, -

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

C:

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

Precedence:

3 1 5 4 2

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/* Program using Arithmetic operator */

#include

#include

void main()

{

int a=5,b=6; // Initializing variablesint c;

clrscr(); // To clear the screen

c=a+b; // + operator

printf(The result is : %d,c);

c=b%a; // % operator


}

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A Relational Operator compares twovalues.

Values can be any built-in C data

type.The comparison involves suchrelationship as equal to, less than

and greater than.The result of the comparison is eithertrue or false.

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Operator Meaning

< Is less than

Is greater than

>= Is greater than or equal to

== Equal to

!= Not equal to

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Operator Meaning

&& Logical AND

|| Logical OR

! Logical NOT

Logical expressions are a compound relational expressions

-An expression that combines two or morerelational expressions

Ex: if (a==b && b==c)

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The AND operator ( && ) requiresboth relationships to be true in orderfor the overall result to be true.

If either or both of the relationshipsare false, the entire result is false.

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Value of the expression

a b a && b

0 0 0

0 1 0

1 0 0

1 1 1

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The OR Operator ( || ) takes two logicalexpressions and combines them. Ifeither or bothare true, the result is true. Both values must befalse for the result to be false.

a b a|| b

0 0 0

0 1 1

1 0 1

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The ( && ) and ( II ) operators alwaysappears between two expressions. Alsoknown as binary operators.

The NOT operator ( ! ) is a unary operator. It precedes a single logical expression and

gives its opposite as a result. Example

if !( marks > 50)is same as

if (marks


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Syntax:

v op = exp;

Where v = variable,

op = shorthand assignment operator

exp = expression

Ex:

x=x+3x+=3

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Simple assignment operator Shorthand operator

a = a+1 a + =1

a = a-1 a - =1

a = a* (m+n) a * = m+n

a = a / (m+n) a / = m+n

a = a %b a %=b

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1. Increment ++

2. Decrement --

The ++ operator adds a value 1 to the operand

The operatorsubtracts 1 from the operand

Eg:

++a or a++

--a or a--

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Let the value of a =5 and b=++a then

a = b =6

Let the value of a = 5 and b=a++ then

a =5 but b=6

i.e.:

1. a prefix operator first adds 1 to the operand and then the

result is assignedto the variable on the left

2. a postfix operator first assigns the value to the variableon left and thenincrements the operand.

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When variable is not in an expression then Pre-incrementing and post-incrementing have thesame effectExampleint c = 5;

++c;printf(%d,c); // c = 6

andc++;

printf(%d,c); // c= 6

are the same

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intc = 5;

printf(%d,++c);

c is changed to 6

Then prints out 6

printf(%d,c++);

Prints out 5 (printf is executed before theincrement)

c then becomes 6

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/* Program using Increment operator */

#include

#include

void main()

{

int a=5,b; // Initializing variablesclrscr(); // To clear the screen

b = a++; // Post Increment operator

printf(The result is : %d,b);

b = ++a; // Pre Increment operator

printf(The res ult is : %d,b);

}

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KGISL ITECH 63

main()

{ 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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Syntax:

exp1 ? exp2 : exp3

Where exp1,exp2 and exp3 are expressions

Working of the ? : Operator:Exp1 is evaluated first, if it is nonzero(1/true) then theexpression2 is evaluated and this becomes the value of theexpression,

If exp1 is false(0/zero) exp3 is evaluated and its value

becomes the value of the expressionEx: m=2;

n=3;

r=(m>n) ? m : n;

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/* Program using Conditional operator */

#include

#include

void main()

{int a,b,c; // Initializing variables

a=5; // Assigning values

b=6;

clrscr(); // To clear the screenc=(a>b)?a:b; // Conditional operator


}

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The conditional operators can be nestedas shown below

void main()

{int k, num = 30;k=(num>5 ? (num


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Operator Meaning

& Bitwise AND

| Bitwise OR

^ Bitwise exclusive OR

> Shift right

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void main(){

clrscr();int a=5,b=6; // a = 0101 , b = 0110int c;c=a&b;printf(a&&b:%d,c); // c = 0100 = 4c=a|b;

printf(a||b:%d,c); // c = 0111 = 7c=a^b;printf(a^b:%d,c); // c = 0011 = 3

int d;d=c1:%d,c); // d = 0001 = 1

}

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1. Comma operator ( ,)

2. sizeof operator sizeof( )

3. Pointer operators ( & and *)

4. Member selection operators ( . and ->)

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One of the essential operations performed ina C language programs is to provide inputvalues to the program and output the dataproduced by the program to a standard

output device. scanf, which can be used to read data from

a keyboard. printf, which sends results out to a terminal.

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Each program that uses standard input / output function must contain the statement.

#include at the beginning.

Single character input output: getchar()

putchar()

String input and output: gets

puts

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#include#include

int main()

{

clrscr();

printf (Welcome to KGISL);

return 0;

}


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#include#includeint main(){

int num;printf(Enter the value of num:);scanf(%d,&num);printf(The value of num is:%d,num);

getch();}


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#include#include

void main()

{

char c;

c=getchar();

putchar( c );

getch();}


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#include#include

void main()

{

char name[10];puts(Enter your name);

gets(name);

puts(Your name is:);

puts(name);getch();

}


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%c- Reads a single character

%f- Reads a floating point value

%s- Reads a string

%h- Reads a hexadecimal integer

%o- Reads an octal integer

%i- Reads an integer value same as %d

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C program is a set of statements, which arenormally sequentially executed in the orderin which they appear.

Conditional statements

Looping statements.

Unconditional statements


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One of the most important parts of anylanguage is the ability to choose toexecute statements based on the value ofa particular variable.

To execute a single statement or group ofstatement.


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There are four types of conditionalstatements.

Simple if statement

Ifelse statement

Nested if statement

Switch case


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If Statement

ifstatement is a basic control flow structure ofC programming language.

ifstatement is used when a unit of code needto be executed by a condition true or false.

If the condition is true, the code in ifblock willexecute otherwise it does nothing.

Only performs an action if the condition istrue.


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Syntax

if (Condition){

statements;

}

If the condition, whatever it is, is true, thenthe statement is executed.

/* D t ti f if t t t */


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/* Demonstration of if statement */

void main( )

{int num ;

printf ( "Enter a number less than 10 " ) ;

scanf ( "%d", &num ) ;

if ( num


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Ifelse StatementTo check more than one condition.

Specifies an action to be performed both whenthe condition is true and when it is false

Syntax:

if (condition)

{true block of statements;

}

else

{

false block of statements;

}

#include


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void main()

{

int a,b;

clrscr();printf(enter values of a and b:\n);

scanf(%d%d,&a,&b);

if(a>b)

{

printf(a is greater:%d,a);

}

else

{

printf(b is greater:%d,b);

}

getch();

}

else-ifladderF h ki th diti


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For checking more than one conditionsSyntax:

if(condition-1){

/* code block if condition-1 is true */}else if (condition-2){

/* code block if condition-2 is true */}else if (condition-3){

/* code block if condition-3 is true */}

else{/* code block all conditions above are false */

}

#include else


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#include

void main()

{

int a,b,c;clrscr();

printf(enter values ofa,b,c:);

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

if(a>b)&&(a>c)

{

printf(a is greater);

}else if(b>a)&&(b>c)

{

printf(b is greater);

}

else

{

printf(c is greater);

}getch();

}

S t

Nested ift t t


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Syntax:if(condition){

if(condition){if statement;

}else{

else stmt;}

}else if{

else if stmt;}

else{

else stmt;}

statement

void main()

{else if (b > c)


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{

int a,b,c;

clrscr();

printf("Enter values ofa,b,c:");

scanf("%d%d%d",&a,&b,&c);

if (a > b)

{

if (a > c){

printf("A is greater");

}

else

{printf("C is greater");

}

}

{

printf("b is greater");

}

else

{

printf("c is greater");

}

getch();}


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Loops Cause a section of your program tobe repeated a certain number of times.

The repetitioncontinues while a conditionis true. When condition becomes false, the

loops ends and control passes to thestatements following the loop.

Types of Loops

for loop while loop

do while loop

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The for allows us to specify three things about aloop in a single line.

a)Setting a loop counter to an initial value.

b)Testing the loop counter to determine whether itsvalue has reached the number of repetitionsdesired.

c)Increasing the value of loop counter each time

the program segment within the loop has beenexecuted.

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The general form offor statement is as under.

for (initialization expression; test expression; incrementexpression)

{statement 1;

statement 2;

.

.statement n;

}

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void main ( ){

int j;

for ( j=0; j < 15; j++ )

{

printf(%d\n,j);

}

getch( );}

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Loops can also be nested. The placing of one loop inside the body of

another loop is called nesting.

Syntax:

for( intialization; test _condition; Increment;)

{

for( intialization; test_condition;increment;)

{

statemet;

}

statement;

}

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#includevoid main ( ){int i, j;clrscr ( );for (j=1; j


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Loops can also be nested like if statements.void main ( ){

int r, c, sum;for ( r = 1; r


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The while loop allows programs to repeat astatement or series of statements, over andover, as long as a certain test condition istrue.

The while loop is an entry-condition loop

Syntax:while (test-condition)

{

statement

}

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#includevoid main(){int i=0;clrscr();

while(i


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The do-while loop is similar to the while loop,except that the test condition occurs at the endof the loop.

The do-while loop is an exit-condition loop.

Syntax

do

{

statement

} while (condition);

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#includevoid main()

{

int i=0;

do{

i++;

printf(%d,i);

}while(i


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KGISL ITECH

Unconditional statement

This statement will be executed without anycondition.

Goto

Break Continue

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The goto statement is a jump statement whichjumps from one point to another point within afunction.

Syntax

goto ;

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Example: goto statement

#include #include int main()

{ int a = 0; n: //Label

printf("\n %d",a); a++; if(a


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break statement Causes immediate exit from the loop

Used in while, for, dowhile or switchstatements

continue statement Skips remaining statements in loop body and start

from the beginning of loopUsed in for loop, while , dowhile loops

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void main ( ){int k;for ( k= -5; k < 25; k= k+5){

printf(%d,k);printf(Good day\n);;

}}

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void main ( ){

int k;for ( k= -5; k < 25; k= k+5)

{printf(%d\n, k);break;printf(Good day);

}}

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void main ( ){int k;for ( k= -5; k < 25; k= k+5)

{printf(%d, k);conitnue;printf(Good Day);

}}

KGISL ITECH

Example: break & continue statement

#include


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#includevoid main()

{ int i;for(i=0;i

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C Intro Class1

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