C Programming Language (Features and Components)

Mangalayatan University
Faculty Name :- Prof. LALIT MOHAN GUPTA
Course Name :- Programming with ‘C’
Course Code :- CSM – 6151
Semester :- 1
Class No. :- 3
Block No. :- 2
UNIT No. :- 5,6
9/21/2024 CSM – 6151 Programming with "C" 1

C Tokens
C Character Set
Features of C
C components
Introduction to C Programming
9/21/2024
CSM – 6151 Programming with "C"
2
Introduction to C Programming & components

High Level Programming Language with some low level features.
Stable language.
Simple Language.
Large Number of Operators.
Less Number of Keywords (only 32 keywords)
Supports pointers to refer computer memory, arrays, structures and
functions.
Structured Programming Language.
Extensible Language
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3
Features of C

The Character set (a-z, A-Z, 0-9, {, }…)
The data types (int, char, float, double, array,
struct, union)
Constants (24, 45.67, ‘X’, “Hello”)
Variables (a, b)
Keywords (int, for, if, else, break)
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Components of C Language

Alphabets (A,..,Z,a,..,z)
Digits(0-9)
Special
Symbols(@,.,;,:)
White
Spaces(n,b)
Operators(+,-,/,%)
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C-Character Set

Tokens are
the basic
building
blocks in C
language.
It is the
smallest
individual
unit in the C
program.
C program
is
constructed
by using
combination
s of these
tokens.
C token can
be
categorized
in five
forms:
Keywords
Identifiers
Constants
Operators
Special
symbols
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6
C Tokens

Keywords
have
predefined
meaning
and they
are used to
perform
specific
task.
Also known
as Reserve
words.
Have fixed
meaning.
Always
written in
lowercase.
32 keywords
in C
programming
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Keywords

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Keywords
auto continue double float int short struct unsigned
break const else for long signed switch void
case default enum goto register sizeof typedef volatile
char do extern if return static union while

Identifiers are used to name various program elements such as
variables, functions and arrays.
Variable is the named memory location that is used to hold a
value that can be modified during the execution of the program.
Declaration of variable:
• datatype var_name;
• e.g. int x;
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Identifiers

May consist of alphabets, digits and underscore ( _ ).
Must not start with a digit.
Keywords can not be used.
White spaces are not allowed.
Only first 31 characters are significant.
Examples: sum, a, x2, first_name, _SI.
Some Invalid identifiers
Simple interest,@abc,12_dfr etc.
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Rules for Naming Identifiers

Constants are
values that
can’t change
during the
execution.
known as
literals.
Types of
constants:
Character
constants
Integer
constants
Floating
constants
Strings
constants
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Constants

A constant of
integer type
consists of
sequence of
digits.
For example :
1, 234, 567, -
4563.
By default
integer literal
are of type int.
Wrong
representation
• 123 456
• 12,34,567
• $234
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Integer Constants

A floating constant
consists of an
integer part, a
decimal point, a
fractional part and
exponent field
containing an e or
E followed by an
integer.
The
Fraction
part and
integer
part are
sequence
of digits.
For
example
0.02, -
23.567, -
4.57E-
23,
3.4e+25,
.98
By
default
floating
literal
are
double.
Invalid
real
constants
: 9.88.7,
5.6E 23,
• 3.4E9.
4
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Real or Floating Constants(CO1)

Character constants
A character constant consists of a single character enclosed in
single quotes.
For example ‘a’ , ‘D’ and ‘@’.
Characters are stored using machine characters sets using ASCII
codes.
All escapes sequences are also characters sequences.
String constants
A string constant is a sequence of characters enclosed in double
quotes.
For example “a”, “ABC”.
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Character constants

An escape sequence is a sequence of characters that does not
represent itself when used inside a character or string literal, but
is translated into another character.
used in formatting the output in output functions.
It represents only one character. However, it consists of two
characters.
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Backslash Character Constants

Constants Hexadecimal Value Meaning
a 07 audible alert (bell sound)
b 08 back space
n 0A new line
r 0D carriage return
f 0C form feed
t 09 horizontal tab
v 0B vertical tab
’ 27 single quote
’’ 22 double quote
? 3F question mark
5C backslash
nnn any octal number
xhh Any hexadecimal number
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Backslash Character Constants

Every combination starts with back slash()
They are non-printing characters.
It can also be expressed in terms of octal digits or hexadecimal
sequence.
Each escape sequence has unique ASCII value.
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Characteristics of escape sequences

Documentation Section
Preprocessor Directives
Global Declaration Section
void main()
{
Local Declaration Section
Statements
}
Other functions as required
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Structure of C program

/*C Program to Display Welcome message*/
#include<stdio.h>
#include<conio.h>
void main()
{
printf(“Welcome to the world of C.”);
getch();
}
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First C program
Documentation Section
Preprocessor Directives
Statements
Welcome to the world of C.

STRUCTURE (LAYOUT) OF C PROGRAM
// Sample of C Program(documentation Section)
#inclufe<stdio.h> // link section
#include<conio.h> // link section
#define pi 3.14 // definition section
int a=10; // global variable declaration
void disp(); // global function declaration
void main() // main function definition
{
float area,r;
printf(“enter radius”);
scanf(“%f”,&r);
area=pi*r*r;
printf(“area=%f”,area);
disp();
getch();
}
20

STRUCTURE (LAYOUT) OF C PROGRAM
Example
void disp() // user defined function definition
{
printf(“hello”);
}
l 21

Pre-processor works under the control of set of instructions,
called preprocessor directives.
These are executed before the compilation process.
These statements begin with # symbol.
Examples:
• #define
• #include
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Pre-processor Directives

A data type is used to declare variables that specifies
• Size of memory allocated to variables.
• Define the range of allowed values.
• Operations that can be performed on those values.
Storage representation of different data types is different in
memory.
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Data Types(CO1)

ANSI C supports
Three classes of
Data Types
Primary or
fundamental or
primitive or built-in
or basic data types.
int , char, float , void
Derived data types
array, function,
pointer
User Defined data
types
enum, typedef
,structure,
union
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Data Type

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Data Type
char
int
float
void
unsigned
signed
short
int
long
float
double
long double
1 Byte
1 Byte
2 Bytes
2/4 Bytes
4 Bytes
4 Bytes
8 Bytes
10 Bytes

Data type modifiers are
keywords used to
change the current
properties of data
types.
Type for
Data
modifiers
:
size
Modifiers
short
long
sign
Modifiers
signed
unsigned
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Data Modifiers

Basic
DATA
TYPE
DATA TYPE with
type modifier
FORMAT
SPECIFIE
R
SIZE RANGE
char
char
signed char
%c 1 Byte -128 to 127
unsigned char %c 1 Byte 0 to 255
int
int
signed int
short
short int
Signed short int
%d
%i
%hi
2 Byte
Or
4 Byte
-32768 to 32767
Or
-2,147,483,648 to
2147,483,647
unsigned
unsigned int
Unsigned short int
%u
%hu
2 Byte
Or
4 Byte
0 to 65535
Or
0 to 4,294,967,295
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Primary Data Types(CO1)

Basic
DATA
TYPE
DATA TYPE with type
modifier
FORMAT
SPECIFI
ER
SIZE RANGE
int
long
long int
signed long int
%ld
%li
4 Byte -2,147,483,648 to
2147,483,647
unsigned long
Unsigned long int
%lu 4 Byte 0 to 4,294,967,295
float
float %f
%e or %E
%g or %G
4 Byte +(1.17*10-38 to 3.4*1038 )
And
-(1.17*1038 to 3.4*1038 )
double
double %lf 8 Byte +(2.22*10-308 to 1.79*10308)
And
-(2.22*10308 to 1.79*10308)
long double %Lf 10 Byte +(3.4*10-4932 to 1.1*104932)
And
-(3.4*10-4932 to 1.1*104932)
void -- -- -- --
Primary Data Types

Type casting is a way to convert a variable from one data type to
another data type. For example, if you want to store a long value
into a simple integer then you can type cast long to int.
There are two types of Type Casting
• Implicit type conversion
• Explicit type conversion
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Type Casting or Type Conversion(CO1)

In this the data
type/Variable of
lower type is
converted to a
higher type.
This automatic
conversion is
known as
implicit type
conversion or
promotion.
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Implicit Type Conversion

When we want to convert a type forcibly in a way that is
different from automatic type conversion, we need to go for
explicit type conversion.
Lower to higher and higher to lower both type conversion can be
done in type casting.
Syntax
• (type name) expression;
• For e.g.
• x = (float)y;
• Where x is of type float and y is of type int.
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Explicit Type Conversion

• 8.5 is converted to integer 8 by
truncation
x=(int) 8.5
• Evaluated as 23/7 and the result
would be 3
a = (int) 23.6/(int)7.2
• Division is done in floating point
mode
b= (double)sum/n
• Result of a+b is converted to
intger.
c= (int)(a+b)
• a is converted to integer and then
added to b.
p= (int)a+b
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Explicit Type Conversion or Type Casting

Standard input or stdin is used for taking input from devices
such as the keyboard as a data stream
Standard output or stdout is used for giving output to a device
such as a monitor.
For using I/O functionality, programmers must
include stdio header-file within the program.
Standard I/O

Reading Character from the keyboard:
• getchar() function can be used to read a single character
Syntax:
var_name = getchar();
Example:
Standard I/O
#include<stdio.h>
void main()
{
char title;
title = getchar();
}

Writing Character to the monitor
• putchar() function can be used to display a single character on
the screen
Syntax:
putchar(var_name);
Example:
Standard I/O
#include<stdio.h>
void main()
{
char title =‘t’;
putchar(title);
}

Formatted input function takes an input data a specific format. It
allows by scanf() function
Syntax:
scanf(“control string”,&arg1,&arg2..);
Example:
Standard I/O
#include<stdio.h>
void main() {
int var1;
scanf("%d ", &var1,
);
}

Formatted output function displays a data in a specific format
on the screen. It allows by printf() function
Syntax:
printf(“control string”,arg1,arg2..);
Example:
Standard I/O
#include<stdio.h>
void main() {
int var1= 60;
printf("%d ", var1, );
}

There are three type
of errors can occur in
the c Programming.
Syntax
Error
Occurs
due to
incorrect
syntax
used in C-
statements.
Found at
compile
time
Logical
Error
Occurs
due to
incorrect
logic used
in C –
statements
by user.
Found
after
execution
i.e may
give
incorrect
output
Runtime
Error
Code links and
compiles just
fine, but during
execution, it
does something
illegal.
Errors

Examples
Syntax Error
void main()
{
printf(“ value of x
%d”,x):
/* x is not declared and
semicolon missing*/
}
Logical Error
floataverage(floata,floatb)
{
return a+b/2;
/* should be (a + b) / 2 */
}
Runtime
Error
int a;
printf("type an integer");
scanf("%d", a);.
Errors

Source code
• The input program
of compiler is known
as source code.
• It can be in any high
level programming
language
• It is human readable
code.
Object code
• The output program
of compiler is known
as object code
• It is machine
language code.
• It is machine
readable code
Executable Code
• Executable code is
generated after
linking all the object
module after
compilation.
Object Code and Executable Code

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Translation of Codes

A variable is a name which is assigned to a data value at storage
location in computer’s memory.
Variables are used to store various kinds of data during program
executions.
Variables name assigned before it use and it can be letter , digit
and an underscore(_).
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Variables and Memory allocation

• Syntax:
• <data type> <variable Name>;
Declaration:
• int num;
• char name;
Example:
• Two type of initialization
Initialization:
• int num=10; //at time of declaration
Example1:
• int num;
• num=10; // after the declaration
Example2:
Declaration and Initialization

Write a program of find area of circle
Write a program of find area of triangle.
Write a program of find swap two numbers using third variable
Write a program of swap two numbers without using third variable
Write a program of swap two numbers without using third variable
Write a program of find area of circle.
Write a program of find area of triangle.
Write a program of find swap two numbers using third variable.
Write a program of swap two numbers without using third
variable
Programs

/* Area of Circle*/
#include<stdio.h>
#include<conio.h>
void main()
{
float r, area;
clrscr();
printf(“enter radiusn”);
scanf(“%f”,&r);
area=22*r*r/7;
printf(“area of circle is=%f”,area);
getch();
}
Program
OUTPUT:
Enter radius:
2
area of circle is =6.28

/* Area of Triangle*/
#include<stdio.h>
#include<conio.h>
#include<math.h>
void main()
{
float a,b,c, area,s;
clrscr();
printf(“Enter sides of trianglen”);
scanf(“%f%f%f”, &a, &b,&c);
s=(a+b+c)/2;
area=sqrt(s*(s-a)*(s-b)*(s-c));
printf(“area of Triangle is=%f”,area);
getch();
}
Program
OUTPUT:
Enter sides of triangle:
3
3
2
area of triangle is = 0.44

/* Swap Two Numbers using third variable*/
#include<stdio.h>
#include<conio.h>
void main()
{
int a,b,temp;
clrscr();
printf (“enter two numbersn”);
scanf (“%d %d ” ,&a ,&b );
temp=a;
a=b;
b=temp;
printf(“After swap numbers are:n a=%dnb=%d”,a,b);
getch();
}
Program
OUTPUT:
Enter two numbers
20
30
After swap numbers are:
a=30
b=20

/* Swap Two Numbers without using third variable*/
#include<stdio.h>
#include<conio.h>
void main()
{
int a,b;
clrscr();
printf (“enter two numbersn”);
scanf (“%d %d ” ,&a ,&b );
a=a+b;
b=a-b;
a=a-b;
printf(“After swap numbers are:n a=%dnb=%d”,a,b);
getch();
}
Program(CO1)
OUTPUT:
Enter two numbers
20
30
After swap numbers are:
a=30
b=20

 In C-programming what will be the value of r if r=p%q where p=-17 and q=5?
[MTU 2011-12 (Even) Marks 2]
 What is the value of 2^3? [GBTU 2011-12 (Odd) Marks 2]
 Write a program in C to find the greatest number among three numbers using
conditional operator. [GBTU 2013-14 (Odd) Marks 5]
 What will be the output of the following code? [GBTU 2011-12 (Odd) Marks 2]
void main( )
{
int a=5, b=6;
printf(“%dt”,a=b);
printf(“%dt”,a==b);
printf(“%dt%d”,a,b);
}
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Weekly Assignment

 Data types
 Structure of C Program
 Basic of C program
Prerequisite and Recap(CO1)

 Data types
• int , char , float , double and void
 Structure of C Program
• Documentation section
• Preprocessor Directive section
• Global section
• Void main()
 Standard I/O
• printf()
• scanf()
Prerequisite and Recap

Thank You

C Programming Language (Features and Components)

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