C

C/C++ IDE

1. Turbo C,C++ IDE for Windows XP
2. GCC 4.5 for any Linux OS
3. Dev C,C++ for any Windows OS
4. C,C++ Emulator for Windows 7

What is a computer?

A computer is a machine that manipulates data according to a set of instructions

What is Language ?

Set of codes used to write a program (i.e)code- collection of program statement

There are 3 level in Language

1. High level
2. Low level
3. Machine language

High level language

1. Consists of statements
2. Using English words & mathematical notations
3. Used in any computer
4. Easy to understand
5. Eamples: BASIC,PASCAL,FORTRAN,ADA,ALGO,C++, C#,Java,HTML,etc
6. C is Mid level language

Low level language

1. Consists of mnemonics
2. Mnemonics-shortform of word
3. Vary from platform to platform
4. ASSEMBLY LANGUAGE is the best example of the low level language

Machine language

1. Consists of detailed cryptic instructions
2. Using only 0’s and 1’s
3. It can be understand by only computer
4. We can’t understand

What is a Program ?

1. Set of instructions
2. Stored - Processor
3. Executed sequencely - Computer
4. Carryout - Specific task
5. Represented - in Binary codes
6. Composed – in Alphabets, Digits, Special symbols

Evolution of Languages

C FEATURES

1. Structured Programming (top down processor)
2. Flexible & Efficient
3. It includes features of low level language
4. Portable ( If same platform of computer)
5. Faster (1:50 => C:BASIC)
6. Ability to extend itself, Case sensitive
7. No. of. Build-in functions
8. Simple & Small
9. Compiler / Interpreter
10. Robust (Build-in functions & Operators)
11. 32 keywords only & uses American Standard Code for Information Interchange( so available only in English )

Compiler and Interpreter

To change source to object file, compile using compiler or interpret using interpreter (c has both compiler as well as interpreter)

1. Interpreter:convert program line by line to machine code
2. Compiler: Convert Whole program to  machine code at one
3. Linker: convert object code into executable machine language

Internal operations

American Standard Code for Information Interchange

Character set used in C

Short Cut Keys In Turbo C Editor

1. F1= Help (to call help of the compiler)
2. F2= Save (to save the program)
3. F3= Open (to open already created program)
4. F5= Zooming window
5. F6= Next window
6. ALT+X= Exit
7. ALT+#= Go to n'th line
8. ALT+F3= Close window
9. ALT+F5= View last output
10. ALT+F7= Interpret
11. ALT+F9= Compile
12. CTRL+F9= Execute
13. SHIFT+DEL= Cut
14. CTRL+INS= Copy
15. SHIFT+INS= Paste
16. CTRL+DEL= Clear/Delete
17. ALT+BACKSPACE= Undo
18. ALT+first leter of the menu= to open that menu

Eg. ALT+F= FILE MENU

How to write your Hello World Program in C

Programming Structure Of C

Syntax

// Documentation text
#include
return-type main(argument)
{
 //Body of the main function
}

Where

1. return-types can be void, int, float, char, double, etc
2. We generally use void as return-type when there is no returning values

FIRST PROGRAM

// This is our first example program
#include
void main()
{
 printf("Hello World");
}

Output:

Welcome to C

Where

1. //-command line
2. #-Preprocessor
3. Include-Directives of C Compiler
4. <>-Tag
5. stdio-Standard input output
6. conio-Console input output
7. .h-Header files
8. main-program where to start execution
9. {}-block

Terminologies

Algorithm:

Steps writing sequencely in simplest way in which program solved

Flowchart

Graphical representation of algorithm where all activities are depicted using symbols as flows

Statement

Single line of the program(made of operator,operands,etc)

Syntax

Refers to the grammer of a programming language

Main Program

1. It is special function
2. CALLED by C system
3. Show starting of the program
4. So every program must have exactly one main function
5. If we have more than one, compiler will confuse

COMMENTS

1. Are non-executable statements
2. Are used for better understanding

Two types of comments in C

1. Single line using //

//first program

2. Multi line using /* */

/*first
program */

Header Files

1. Special source files
2. Contains library functions
3. Library functions are pre-written
4. Used to carry out commonly used routines
5. To use the library function ,we should include the header file where the function

Syntax:

#include<headerfile.h>

Where

1. Filename - header file name

Commonly used Header files

1. stdio- Standard I/o library functions
2. conio - DOS console I/o routines
3. string- String manipulation functions
4. math- Mathematical functions
5. stdlib- utility function(conversion routines, search/sort routines, and other miscellany.)
6. ctype-Character testing & conversion functions

C Tokens

The following are 6 types of tokens in C

1. Keywords
2. Constants
3. Strings
4. Operators
5. Identifiers
6. Special symbols

Keywords

1. They have fixed predefined meaning
2. We can't change
3. 32 key words in ANSI C
4. Keywords should be in lowercase
5. Another name reserved words

List of Keywords

Identifiers

1. Used defined name- variable, function, array.
2. Consists - sequence of letters,digits,underscore
3. First character - alphabet/ underscore
4. Length- max. 31 characters
5. Can't use Keywords & White spaces
6. Case sensitive
7. Valid Example: AO, disks, I, i
8. Invalid Example: AO/, auto, 56

Constants

Fixed value, do not change even during execution

Types of Constants

Numeric Constant

1. Must have atleast one digit
2. May be +ve / -ve
3. decimal point is allowed only for real constants
4. Can't use White spaces & Commas

Character Constant:

1. Must have atleast one character
2. Can be single Alphabet/Digit/Special symbol
3. Enclosed within ' ' for single character constants
4. Enclosed within " " for string constants

Variables

1. Simply Changeable values
2. It can take different values at different times during execution

Operators

1. Symbols that perform operation on data
2. C supports rich set of built-in operators

Special Symbols

1. They are such as [ ] { } < > ( ) / \ . , ? " ' ; : ! @ # $ % ^ & * _ - = + | ~ `

String

1. Sequence of character
2. Enclosed within double quotes (“”)
3. Character - letters, numbers, special characters, blank spaces
4. Case sensitive: 'A' ≠ 'a', 'A' ≠ "A"

Example: "haRIsh", "ha rish", "har@ish", "1har+ish5"

Escape Characters

1. These are used in output functions
2. They are not two characters, It is single
3. They are known as escape sequence, backslash characters

List of Escape Characters

Data Types

Used to specify the type of the date so that we can easily classify our operations

Primitive Data Types: char, int, float, double

Derived Data Types: Array, Pointer, Function

User Defined Data Types: enum, struct, union

Where: signed, unsigned, short, long are Data type modifier

Declaration

All variables must be declared before it is used to reserve memory storage area for that variable. Syntax:

Data-type Variable-list;

Where:

1. Data Type:int,char,float,double,etc
2. Variable-List:list of variable separated by commas

Example:

int a;
int harish;
float b,chitra;

Initialization and Value Assignment

Initialization: First assignment of value to the variable is called initializing

1. To store int numbers dont use decimal point

int a;
a=5;//Declare and assign by two steps (or)
int a=5;//Declare and assign by single step

2. To store float number can use decimal points(7 digits after precision)

float a;
a=5.6549870;//Declare and assign by two steps (or)
float a=5.6549870;//Declare and assign by single step<

3. To store double numbers can use decimal point (14 digits after precision)

double rs;
rs=5.01234567890123;// Declare and assign by two steps(or)
double rs=5.01234567890123;//Declare and assign by single step

4. To store single character

char a;
a=‘n’;//(or)
char a=‘n’;

5. To store sequence of character(String)

char a[10];
a=“harish”;//(or)
char a[10]=“harish”;

Input & Output Functions

1. To interface the user and computer I/O functions are used
2. To display message, output, warning
3. To get input from the user
4. These are available in appropriate header files such as stdio.h, conio.h, etc

List of Type Specifiers

printf() from stdio.h

Syntax

printf(“control string”,arg-list);

Displaying text message

Example:

printf("What is this");

Output:

What is this

Displaying variable values using type specifier

Example:

int a=5;
printf("result: %d",a);

Output:

result: 5

Note: %- shows the content of the variable

Displaying escape characters

Example:

printf("well \ncome");

Output:

well
come

scanf() from stdio.h

Syntax:

scanf(“control string”,&arg-list);

Reading a value

Example:

int a;
scanf("%d",&a);

Reading no.of values

Example:

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

Note: &- shows address of the variable

Unformatted I/O

Reading a character

To get a single character from the user

stdio.h

1. getchar()-display the character while typing the character

conio.h

1. getch() - won’t display the character while typing the character
2. getche() - display the character while typing the character and echo it again

Writing a character

To display a single character to user

1. putchar(), putch() - both are used to display the character which is passed through it.
2. fflush() - method is used to clear the unwanted dummy values in the variable
3. clrscr() - method is used to clear the last out in the output screen

Note: we usually include our final statement as getch() method in our program,which just makes wait for our respond for exiting from the output.Otherwise we used to see the output by seeing the last output window (alt+f5)
Example 1

#include<stdio.h>
void main()
{
 float a;
 printf("Enter the value for A:");
 scanf("%f",&a);
 printf("Enterd value: %f",a);
}

Output:

Enter the value for A:4.52
Entered value:4.520000

Example 2

#include<conio.h>
void main()
{
 char a;
 Printf("Enter a character: ");
 a=getche();
}

Output:

Enter a character: j
j

Example 3

#include<stdio.h>
void main()
{
 char a;
 printf("Enter A value:");
 a=getchar();
 printf("Entered value: ");
 putchar(a);
}

Output:

Enter A value: j
Entered value: j

Example 4

#include<conio.h>
void main()
{
 char a;
 printf("Enter A value:");
 a=getch();
 printf("Entered value:");
 putch(a);
}

Output:

Enter the value:
Entered value:j

8 TYPES OF OPERATORS

1. Arithmetic
2. Relational
3. Logical
4. Assignment (short hand)
5. Increment decrement
6. Conditional
7. Bitwise
8. special

Arithmetic Operator

To perform arithmetic operation such as addition, subtraction, multiplication, division and modulo operation on numeric
 

//Example Program
#include<stdio.h>
void main()
{
 int a=10,b=5,c;
 c=a+b;
 printf("ADD: %d",c);
 c=a-b;
 printf("SUB: %d",c);
 c=a*b;
 printf("MUL: %d",c);
 c=a/b;
 printf("DIV: %d",c);
 c=a%b;
 printf("MOD: %d",c);
}

Output:

ADD:15 SUB:5 MUL:50 DIV:2 MOD:0

Relational Operator

To find relationship between two operands and its result will either -true(1) / false(0)

20>30  false
20<30  true
25>=30 false
25<=25 true
25==30  false
25!=30 true

Logical Operator

To find the relation ship between two or more relational expressions and its result will either true(1) / false(0)

((20>30)&&(20<30))  False
  false          true
((20>30)||(20<30))  True
  false          true
!(20>30)  True
  false

Shorthand Assignment Operator

To simplify certain statement (operator =) Syntax:

variable-name arithmentic = expression

Example:

int a=5,b=6;
a+=b;
printf("a: %d",a);

Output:

a=11;

Increment and Decrement Operator

Increment Operator(++)

Syntax:

variable++ (or) ++variable

Pre Increment Example:

int a=5,b; 
b=++a;
printf("a=%d, b=%d",a , b);

Output:

a=6, b=6

Post Increment Example:

int a=5,b;
b=a++;
printf("a=%d, b=%d",a , b);

Output:

a=5, b=6

Note: we may use only one operand int a=5; a++; printf("a=%d", a); Output:

a=6

Decrement Operator(--)

Syntax:

variable-- (or) --variable

Pre Decrement Example:

int a=5,b; 
b=--a;
printf("a=%d, b=%d",a , b);

Output:

a=4, b=4

Post Decrement Example:

int a=5,b;
b=a--;
printf("a=%d, b=%d",a , b);

Output:

a=4, b=5

Note: we may use only one operand

int a=5;
a--;
printf("a=%d", a);

Output:

a=4

Conditional Operator

Builds simple conditional expression Syntax:

Conditional-Expresion ? True-Statement: False-Statement

Example:

5>6 ? printf("true") : printf("false");

Output:

false

Special Operators

Comma (,)

1. To link releated Expression
2. Evaluated from left to right

Example:

int a=5,b=6;

Sizeof

1. To get the size of the operand
2. Used to dynamic memory allocation of like array and structures

Example:

int a=5,b;
b=sizeof(a);
printf("Size of int variable a:%d",b);

Output:

Size of int variable a:2

Bitwise Operators

1. Bit by bit manipulation
2. Can’t be applied on float or double
3. Require two integer type operands
4. Refer table of logical operator

Example AND

a=5,b=6,c
c=a&b;
//a=0000 0000 0011 0101
//b=0000 0000 0011 0110
//c=0000 0000 0011 0100
printf("c=%d",c);

Output:

c=4

Example OR

a=5,b=6,c;
c=a|b;
//a=0000 0000 0011 0101
//b=0000 0000 0011 0110
//c=0000 0000 0011 0111
printf("c=%d",c);

Output:

c=7

Example XOR

a=5,b=6,c;
c=a^b;
//a=0000 0000 0011 0101
//b=0000 0000 0011 0110
//c=0000 0000 0000 0011
printf("c=%d",c);

Output:

c=3

Example NOT

a=5;
c=^a;
//a=0000 0000 0011 0101
//c=1111 1111 1100 1010 overflow
printf("c=%d",c);

Output:

c=-6(over flow)

Example Right shift

a=5,b;
b=a>>2;
//a= 0000 0000 0011 0101
//b= 00 0000 0000 0011 01--
printf("b=%d",b);

Output:

b=1

Example Left shift

a=5,b;
b=a<<2;
//a=0000 0000 0011 0101
//b=---00 0000 0011 0101 00
printf("b=%d",b);

Output:

b=20

Operator Presedence

How to evaluate the equation

Example 1

A=9-12/3+3*2-1

Steps:

A=9-4+3*2-1
A=9-4+6-1
A=5+6-1
A=11-1
A=10

Example 2

A=9-12/(3+3)*(2-1)

Steps:

A=9-12/6*(2-1)
A=9-12/6*1
A=9-2*1
A=9-2
A=7

Expressions

1. Arithmetic
2. Relational
3. Logical

Syntax:

Variable=Expression;

Arithmetic Expressions

It contains collection of constants, variables and arithmetic operator and results a numeric value

x=5*6-6+4/3;

Relational Expresssions

It contains collection of constants, variables and relational operator and results either true(1) or false(0) value

x=(5==6);

Logical Expression

It contains collection of relational expressions and logical operators and results either true(1) or false(0)

x=(a<5)&&(b==2)||(c!=1);

Type Casting

1. Converting form one type to another type
2. Small in Big, not Big in Small (memory space)

Types of Type Casting:

1. Implicit Type Casting
Example:

int x=5;
float y=6.2,z;
z=x+y;//z as floating

2. Explicit Type Casting
Syntax:

Type (var) (or) (Type) var

Example:

x=(int)y+.5;//x as floating