Introduction to c programming

C PROGRAMMINGTUTORIAL

By Ms. P. P. Jaini

OUTLINE Overview History Features Role of C Compiler Flowchart Sample C Program 1 Character Set Data Types Variables C is Case Sensitive C Token Sample C Program 2 Control Statements Common Programming Errors Assignment

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OVERVIEW OF C C language is

Structured

High level

Machine independent

Follows top down approach

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HISTORY ALGOL

In 1960’s First language using a block structure

BCPL In 1967 Basic Combined Programming Language

B In 1970 Added feature of BCPL

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CONTD…

CEvolved from ALGOL, BCPL & B

Developed between 1969 and 1973 along with Unix

Developed at AT & T’s Bell Laboratories of USA

Designed and written by Dennis Ritchie

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FEATURES C is PortableThis means a program written for

one computer may run successfully on other computer also.

C is fast This means that the executable program

obtained after compiling and linking runs very fast.

C is compact The statements in C Language are generally

short but very powerful.6

CONTD…

Simple / Easy

The C Language has both the simplicity of High Level Language and speed of Low Level Language. So it is also known as Middle Level Language

C has only 32 Keywords

C Compiler is easily available

C has ability to extend itself. Users can add their own functions to the C Library

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ROLE OF C COMPILERCompiler: converts source to object code for a specific platformLinker: resolves external references and produces the executable

module Typically C programs when executing, have four different files

Source Code – file that is created by user and the executable statements are written. This file is saved with a file extension of ‘.c’.

Header files – contains the declaration of functions and pre-processors statements. Header files have ‘.h’ as their extension.

Object files – are the output from the compilers. ‘.o’ or ‘.obj’ are the typical extension to such files.

Binary executables – are an output of the process of linking. Binary executables have ‘.exe’ as their extension.

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FLOWCHART Flow charts are symbolic diagrams of operations

and the sequence, data flow, control flow and processing logic in information processing.

These charts are used to understand any working sequence of the program.

Flow char is a graphical representation of algorithm. I

An algorithm defines as the step by step procedure or method that can be carried out for solving programming problems.

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CONTD…Advantages of flowchart:-

It provides an easy way of communication because any other person besides the programmer can understand the way they are represented.

It represents the data flow.

It provides a clear overview of the entire program and problem and solution. 10

CONTD…

It checks the accuracy in logic flow.

It documents the steps followed in an algorithm.

It provides the facility for coding.

It provides the way of modification of running program.

They shows all major elements and their relationship.

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FLOWCHART SYMBOLS

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CONTD… Terminator This symbol represents the beginning and

end point in a program. We use start and stop option in it.

Input / Output Symbol This symbol is used to take any input or

output in the algorithm.

Process Symbol A rectangle indicates the processing,

calculation and arithmetic operations 13

CONTD… Decision Symbol It is used when we want to take any decision in

the program.

Connector Symbol This symbol is used to connect the various

portion of a flow chart. This is normally used when the flow chart is split between two pages

Data Flow Symbol This symbol is used to display the flow of the

program. It shows the path of logic flow in a program. 14

SAMPLE C PROGRAM

main() --------------Function name { ------------Start of Program

…. …. -------- Program statements ….

} --------------- End of Program

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CONTD…

#include <stdio.h>

void main ( ) { printf ( “Hello, World!\n);

}

#include <stdio.h> int main ( void ) { printf ( “Hello, World!\n” ) ; return 0 ; }

/* Filename : hello.c Description : This program prints the greeting “Hello, World!” */

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FLOWCHART FOR HELLO.C

int main (){ printf("Hello, world!\n");}

An oval denotes either the start or the end of the program, or a haltoperation within the program (which we’ll learn about later).

A parallelogram denotes either an input operation or an output operation.

An arrow denotes the flow of the program.

Start

End

Output “Hello, world!”

CONTD…

CommentsText surrounded by /* and */ is ignored by computerUsed to describe program

int main()Program’s execution starts from the main functionParenthesis used to indicate a function int means that main "returns" an integer valueBraces ({ and }) indicate a block

The bodies of all functions must be contained in braces

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CONTD…o Preprocessor directives

#include <stdio.h>#include <conio.h>#include <stdlib.h>#include <string.h>

The #include directives “paste” the contents of the files like stdio.h and conio.h into your source code, at the very place where the directives appear.

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CONTD… These files contain information about some library

functions used in the program:stdio stands for “standard I/O”, conio stands for “console I/O”stdlib stands for “standard library”,string.h includes useful string manipulation functions.

Want to see the files? Look in /TC/include

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CONTD… #define MAX_COLS 20 #define MAX_INPUT 1000

The #define directives perform “global replacements”:

every instance of MAX_COLS is replaced with 20, and every instance of MAX_INPUT is replaced with 1000

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CONTD…

commonly used stdio.h functions:

printf() – Output functionSyntax:

printf(“….”) ;

scanf() – Input functionSyntax:

scanf(“format specifier”, &var,&var2…); 22

CONTD…

commonly used conio.h functions:

clrscr()Used to clear the screen

getch()Used to get a character from ouput screen to

come into the edit screen.

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CHARACTER SET

These are the characters that C recognizes.

Letters (upper case and lower case)A B C D E F G H I J K L MN O P Q R S T U V W X Y Za b c d e f g h i j k l mn o p q r s t u v w x y z

Digits0 1 2 3 4 5 6 7 8 9

Special Characters (punctuation etc)space (also known as blank)’ " ( ) * + - / : =! & $ ; < > % ? , .ˆ # @ ˜ ‘ { } [ ] \ | 24

CONTD… 256 characters are allowed in C.

A – Z : 65 to 90 26a – z : 97 to 122 260 – 9 : 48 to 57 10Special symbols[ #, &, `…] 32Control characters[\n, \t . ..] 34Graphic characters 128

Total 25625

DATA TYPES

1] Primary Integer Float Double Character

2] Derived Arrays Pointers Structure

o C support several different types of data, which may be represented differently within the computers memory.

o Types

3] User Defined typedef enum

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CONTD… Primary Data Types

Data Types Byte Format Specifier 1] char 1 %c signed char 1 %c unsigned char 1 %c

2] short 2 %d short signed int 2 %d short unsigned int 2 %u

3] int 2 %d signed int 2 %d unsigned int 2 %u 27

CONTD… Data Types Byte Format Specifier

4] long 4 %l

long signed int 4 %ld

long unsigned int 4 %lu

5] float 4 %f

signed float 4 %f

unsigned float 4 %uf

6] double 8 %lf

7] Long Double 10 %Lf28

TYPE CASTING It is used to convert on data at a time.

We can have two types of type casting. Implicit Explicit

Implicit : This converts narrow type to wider type so that use can avoid the information to the system.

Explicit : Explicit type casting is done by the programmer manually. When the programmer wants a result of an expression to be in particular type, then we use explicit type casting. This type casting is done by casting operators ‘( )’ and data type.

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CONTD…

#include <stdio.h>

void main ( ) { int base, height, area; base = 5;

height =3;

area = (base * height)/2; printf ( “Area = %d \n”, area); } Output : Area = 7 ……………………. Incorrect

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CONTD… #include <stdio.h>

void main ( ) { int base, height, area; base = 5;

height = 3;

area = ((float) (base * height)/2); printf ( “Area = %d \n”, area); } Output : Area = 7.5 …………………….Correct

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USER DEFINED DATA TYPE

[A] Type Definition

Allows user to define an identifier that would represent an existing data type

Syntax: typedef type identifier

Eg: typedef int units;

units batch1, batch2;

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CONTD…

[B] Enumerated data type

Syntax: enum identifier { value1, value2... valuen}

Eg: enum day{ Monday, Tuesday, Wednesday, Thursday, Friday, Saturday, Sunday}

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VARIABLES Variable names correspond to locations in the computer's

memory Data name that may be used to store a data value It may take different values at different times during

execution Eg:

char x;char y = ‘e’;

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CONTD… Rules

Must begin with a letter(), some system permits underscore as first character.

Length should be not more than 8 charactersUppercase and lowercase are significant, (i.e.) total

and TOTAL are differentVariable should not be a keywordWhite space is not allowed

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C IS CASE SENSITIVE

C is case sensitive: it distinguishes between UPPER case (CAPITAL) and lower case (small) letters.

Keywords in C — for example, the keyword int — MUST be in lower case. For example:

#include <stdio.h>

int main (){ /* main */

int height_in_cm; height_in_cm = 160;

printf("My height is %d cm.\n",height_in_cm);

} /* main */36

C TOKENS Keywords Identifiers Constants Strings Special Symbol Operators

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CONTD…

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

KeywordsC uses 32 keywordhave fixed meaning and cannot be changed

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CONTD… Constants

Quantity that does not change is called a constant.

TypesNumeric constants

Integer constants – 123, -33Real constants – 0.992, 3.5e2

Character constantsSingle character constants – ‘5’, ‘a’String Constants – ‘Hello’, ‘1999’

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CONTD…Backslash Characters Constants

\n – Newline \b – Backspace \f – Form feed \t – Tab or horizontal tab \a – Audible alert \r – Carriage return \v – Vertical Tab \’ – Single Quote \” – Double Quote \? – Question Mark \\ - Backslash \0 - Null

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CONTD…

IdentifiersNames of arrays, function and variable

OperatorsArithmeticRelationalLogicalBitwise

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ARITHMETIC OPERATORS

C operation

Arithmetic operator

Algebraic expression

C expression

Addition + f + 7 f + 7 Subtraction - p – c p - c Multiplication * bm b * m Division / x / y x / y Modulus % r mod s r % s

CONTD….

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CONTD…. Equality and Relational Operators

Standard algebraic equality operator or relational operator

C equality or relational operator

Example of C condition

Meaning of C condition

Equality Operators = == x == y x is equal to y

not = != x != y x is not equal to y Relational Operators > > x > y x is greater than y

< < x < y x is less than y

>= >= x >= y x is greater than or equal to y

<= <= x <= y x is less than or equal to y

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CONTD….

Logical Operators:&& logical And || logical Or! logical Not

Bitwise Operators & bitwise And | bitwise Or ^ bitwise Xor ~ bitwise Not << shift left >> shift right 44

SAMPLE C PROGRAM 2/* Program for multiplication of two variables */

#include< stdio.h>#include < conio.h>void main(){int a,b,c;clrscr();printf(“Enter two numbers”);scanf(“%d%d”,&var1,&var2);c=a*b;printf (“\n Multiplication of two numbers is %d ”,c);getch();}

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CONTD… OUTPUT:

Enter two numbers: 12 3

Multiplication of two numbers is 36

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CONTROL STATEMENTS

These statements are used to control the flow of program by using these statements. We can have four types of control statements:-

decision making

case control statement or switch statement

looping / iteration statement

jump / branching statement 47

DECISION MAKING These statements are used when we want to

take any decision according to the condition or user requirement. These conditions are used by using ‘if’ statement. We can have four types of conditional statements

if if-else if – else if nested if

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if if statement is simple decision making

statement, which is used to take any decision when the condition is true.

if (statement) { Statement; } if (expression / condition) Statement;

CONTD….

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CONTD…. If-else This statement is used to make decision in C

language. If the given condition is true then the cursor will move to the true portion else it will move to the false portion.

if (condition) { Statement; } else { Statement; } 50

If else-if

if (condition)

{

Statement;

}

else if (condition)

{

Statement;

}

else if (condition)

{

Statement;

}

else

{

Statement;

}

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SWITCH CASE / SELECT CASE

These statements are used with the replacement of if-else and these statements are used when we have multiple options or choices.

These choices can be limited and when we use switch case we can use only integer or character variable as expression.

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Syntax: switch( expression){

case value-1:block-1;break;

case value-2:block-2;break;

----default:

default-block;break;

}statement -X;

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LOOPING These statements are used to control the

flow of the program and repeat any process multiple times according to user’s requirement.

We can have three types of looping control statements.

while

do-while

for

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CONTD…While It is an entry control loop statement, because

it checks the condition first and then if the condition is true the statements given in while loop will be executed.

SYNTAX:- Initialization; while (condition) { Statements; Incremental / decrement; }

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CONTD…

Do-while

Do-while loop is also called exit control loop.

It is different from while loop because in this loop the portion of the loop is executed minimum once and then at the end of the loop the condition is being checked and if the value of any given condition is true or false the structure of the loop is executed and the condition is checked after the completion of true body part of the loop.

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CONTD… SYNTAX:-

Initialization do { Statement; Increment / decrement; } while (condition)

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CONTD….

For loop It is another looping statement or construct used

to repeat any process according to user requirement but it is different from while and do-while loop because in this loop all the three steps of constructions of a loop are contained in single statement.

It is also an entry control loop.

We can have three syntaxes to create for loop:-58

CONTD….

for (initialization; Test condition; Increment / decrement)

{ Statement; }…………………………………….for (; test condition; increment / decrement) { Statement; }………………………………………

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CONTD….for (; test condition;) { Statement; Increment / decrement }

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JUMPS STATEMENTS These are also called as branching statements.

These statements transfer control to another part of the program. When we want to break any loop condition or to continue any loop with skipping any values then we use these statements. There are three types of jumps statements.

Continue

Break

Goto61

CONTD…

Continue This statement is used within the body of

the loop. The continue statement moves control in the beginning of the loop means to say that is used to skip any particular output.

WAP to print series from 1 to 10 and skip only 5 and 7.

#include void main ( ) { int a;

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CONTD…

clrscr ( ); for (a=1; a<=10; a++) { if (a= =5 | | a= = 7) continue; printf (“%d \n”,a); } getch ( ); }

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CONTD…

Break This statement is used to terminate any

sequence or sequence of statement in switch statement. This statement enforce indicate termination. In a loop when a break statement is in computer the loop is terminated and a cursor moves to the next statement or block;

Example:

WAP to print series from 1 to 10 and break on 5

#include void main ( ) {

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CONTD…

int a; clrscr ( ); for (a=1; a<=10; a++) { if (a= =5) break; printf (“%d \n”,a); } getch ( ); }

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CONTD…Goto statement It is used to alter or modify the normal sequence

of program execution by transferring the control to some other parts of the program. the control may be move or transferred to any part of the program when we use goto statement we have to use a label.

Syntax: Forward Loop: goto label; …. …. label: statement; 66

CONTD…

Backward Loop: label:

statement …. …. goto label;

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COMMON PROGRAMMING ERRORS Missing Semicolons

Eg: a = x+y …… is wrong c= b/d; …… is right

Misuse of SemicolonEg:

for(i = 1; i <= 10; i++); sum = sum + i;

is wrong

for(i = 1; i <= 10; i++) sum = sum + i;

is right68

CONTD…

Use of = instead of = = Missing Braces Missing Quotes Improper Comment Characters Undeclared Variables

And many more……

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ASSIGNMENT Write a C program to swap two entered number.

Write a C program to perform all the arithmetic operations.

Write a C program to find the area of a circle, triangle and rectangle.

Write a C program to calculate the area of circle, triangle and rectangle.

Write a C program to get a number from user and print a square and cube of that number. 70

CONTD… Write a C program to display the greatest of

three number using if else statement.

Write a C program to find the number is positive or negative.

Write a C program to find the number is odd or even.

Write a program to display the spelling of number using switch case. 71

Write a C program to display the entered letter is vowel or a character.

Write a C program to display odd number from 1 to n using while loop and do while loop.

Write a C program to display even number from 1 to n using for loop.

CONTD…

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QUERIES?

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THANK YOU!!!

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