Introduction to c programming

C PROGRAMMING
TUTORIAL

By: gajendra singh rathore

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 2
 Assignment

OVERVIEW OF C
 C language is

 Structured

 High level

 Machine independent

 Follows top down approach

3

HISTORY
 ALGOL
 In 1960’s
 First language using a block structure

 BCPL
 In1967
 Basic Combined Programming Language

 B
 In1970
 Added feature of BCPL

4

CONTD…

 C
 Evolved 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

5

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 6
short but very powerful.

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 7
functions to the C Library

ROLE OF C COMPILER
 Compiler: converts source to object code for a specific
platform
 Linker: 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. 8
 Binary executables – are an output of the process of
linking. Binary executables have ‘.exe’ as their extension.

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.

 An algorithm defines as the step by step
procedure or method that can be carried out for 9
solving programming problems.

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. 11

FLOWCHART SYMBOLS

12

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
13
and arithmetic operations

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

SAMPLE C PROGRAM

main() --------------Function name
{ ------------Start of Program
….
…. -------- Program statements
….
} --------------- End of Program

15

CONTD…

/* Filename : hello.c
Description : This program prints the greeting
“Hello, World!”
*/
#include <stdio.h> #include <stdio.h>
int main(void)
void main( ) {
{ printf ( “Hello, World!n” ) ;
printf ( “Hello, World!n”); return 0 ;
getch(); }
}
16

FLOWCHART FOR HELLO.C
An oval denotes either
int main () the start or the end of
{
the program, or a halt
printf("Hello, world!n");
} operation within the
Start program (which we’ll
learn about later).

A parallelogram
Output “Hello, world!”
denotes either an input
operation or an output
operation.
End
An arrow denotes the
flow of the program.

17

CONTD…
 Comments
 Text surrounded by /* and */ is ignored by computer
 Used to describe program
 int main()

 Program’s execution starts from the main function
 Parenthesis used to indicate a function
 int means that main "returns" an integer value
 Braces ({ and }) indicate a block
 The bodies of all functions must be contained in braces

18

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.

19

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

20

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

21

CONTD…
 commonly used stdio.h functions:

printf() – Output function
Syntax:

printf(“….”) ;

scanf() – Input function
Syntax:

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.
23

CHARACTER SET
These are the characters that C recognizes.
Letters (upper case and lower case)
AB C DE F G H I J KLM
NOPQRSTUVWXYZ
abcdefghijklm
nopqrstuvwxyz
Digits
0123456789
 Special Characters (punctuation etc)
space (also known as blank)
’" ( ) * + - / : =
!&$;<>%?,.
ˆ#@˜‘{}[]| 24

CONTD…
 256 characters are allowed in C.

A – Z : 65 to 90 26
a – z : 97 to 122 26
0 – 9 : 48 to 57 10
 Special symbols[ #, &, `…] 32
 Control characters[n, t . ..] 34
 Graphic characters 128

Total 256 25

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

o Types

1] Primary 2] Derived 3] User Defined
 Integer  Arrays  typedef
 Float  Pointers  enum
 Double  Structure
 Character

26

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
27
signed int 2 %d
unsigned int 2 %u

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
28
7] Long Double 10 %Lf

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 user 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 ‘( )’ 29

and data type.

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
30

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

31

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;
32

CONTD…
[B] Enumerated data type

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

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

33

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’;

34

CONTD…
 Rules
 Must begin with a letter(), some system permits
underscore as first character.
 Length should be not more than 8 characters
 Uppercase and lowercase are significant, (i.e.) total
and TOTAL are different
 Variable should not be a keyword
 White space is not allowed

35

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

37

CONTD…
 Keywords
 C uses 32 keyword
 have fixed meaning and cannot be changed

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

38

CONTD…
 Constants
 Quantity that does not change is called a constant.

 Types
 Numeric constants
 Integer constants – 123, -33

 Real constants – 0.992, 3.5e2

 Character constants
 Single character constants – ‘5’, ‘a’

 String Constants – ‘Hello’, ‘1999’

39

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
40
 0 - Null

CONTD…
 Identifiers

Names of arrays, function and variable

 Operators

Arithmetic
Relational
Logical
Bitwise
41

CONTD….
ARITHMETIC OPERATORS

C operation Arithmetic Algebraic C expression
operator 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

42

CONTD….
 Equality and Relational Operators
Standard algebraic C equality or Example of C Meaning of C
equality operator or relational condition condition
relational operator operator
E quality O perators
= == x == y x is equal to y
not = != x != y x is not equal to y
R ela tiona l Op erators
> > 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
43
equal to y

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(); 45
}

CONTD…
 OUTPUT:

Enter two numbers: 12 3
Multiplication of two numbers is 36

46

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

48

CONTD….
 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;
49

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
{
50
Statement;
}

 If else-if
if (condition)
{
Statement;
}
else if (condition)
{
Statement;
}
else if (condition)
{
Statement;
}
else
{ 51

Statement;

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.

52

 Syntax:
switch( expression)
{
case value-1:
block-1;
break;
case value-2:
block-2;
break;
----
default:
default-block;
break;
53
}
statement -X;

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

54
 for

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; 55
}

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. 56

CONTD…
 SYNTAX:-

Initialization
do
{
Statement;
Increment / decrement;
}
while (condition)
57

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;
}
59
………………………………………

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

60

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
61
 Goto

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 ( )
{ 62

int a;

CONTD…
clrscr ( );
for (a=1; a<=10; a++)
{
if (a= =5 | | a= = 7)
continue;
printf (“%d n”,a);
}
getch ( );
}
63

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
64
void main ( )
{

CONTD…
int a;
clrscr ( );
for (a=1; a<=10; a++)
{
if (a= =5)
break;
printf (“%d n”,a);
}
getch ( );
} 65

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;
….
….
66
label:
statement;

CONTD…
 Backward Loop:
label:
statement
….
….
goto label;

67

COMMON PROGRAMMING
ERRORS
 Missing Semicolons
 Eg: a = x+y …… is wrong
c= b/d; …… is right
 Misuse of Semicolon
 Eg:
for(i = 1; i <= 10; i++);
sum = sum + i;
 is wrong

for(i = 1; i <= 10; i++)
sum = sum + i; 68
 is right

CONTD…
 Use of = instead of = =
 Missing Braces

 Missing Quotes

 Improper Comment Characters

 Undeclared Variables

And many more……

69

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 70

and print a square and cube of that number.

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

CONTD…
 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.

72

Introduction to c programming

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