c programming Pankaj Panjwani.pptx

1
C Programming Language
Presented By:
NARAHARI

PROGRAMMING LANGUAGE
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 Program: Set of
 From the time when computers were invented
programming existed.
 Programming was done using a particular set of rules
and syntaxes which is said to be a language used to
write the Program.

EVOLUTION OF ‘C’
3
ALGOL 60 (Programming using Algorithms)
CPL (Combined Programming Language)
BCPL (Basic Combined Programming Language)
‘B’ Developed By Ken Thompson
BCPL + B + Additional Features = ‘C’ Language
Developed By : Dennis M. Ritchie & T BELL
Laboratory, New Jersey, USA in 1972.

FEATURES OF ‘C’
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 Robust Language, for writing any complex program.
 Built-in Functions & Data types.
 Suitable for writing both System Software and Business
Applications.
 Efficient & Faster in Execution.
 Highly Portable.
 Dynamic Memory Allocation (DMA)

STRUCTURE OF A C PROGRAM
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#include<stdio.h>
#define PI 3.14
void main()
{
statements;
……..
}
Preprocessor
Symbol ( # )
Header file
(all files with
Extension *.h)
Symbolic
Constants
Function main()
(Entry point for
any C Program)
Function Block
(main() function
Starting and ending
Limit within { })
Statements;
(all the coding which
to be written for
Execution)
include for including
The file at Preprocessing
< > to locate
The file in the
Default Include
Directory

TOKENS
(The smallest individual unit in a C Program)
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 Identifiers
 Keywords
 Constants
 Special Characters

IDENTIFIERS
7
 Identifiers can be defined as the name of the
variables and some other program elements.
 It can be the combination of the following characters.
Alphabets (a-z, A-Z), Numbers (0-9) & Underscore ( _
).
 All the names used to refer an element in a program
is said to be Identifier.
 Examples of some valid identifiers name, mark1,
total_marks, _avg

KEYWORDS
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 Keywords are also identifiers but cannot be user defined
since they are reserved words.
 Keywords are some special words for which the meaning
is already known to the compiler.
 All the keywords should be in lower case letters.
 Examples for some keywords are if, break, else, return,
void, etc.

CONSTANTS
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 Constants are of three types :
1) Literal Integer Constants.
2) Literal Floating point Constants.
2) Literal Character Constants.
3) Literal String Constants.
 Literal Integer Constants are all positive and negative numbers like
1, -5, 1548, -58469, etc.
 Literal Floating point Constants are all decimal numbers like 12.25,
0.564, 56.e38, etc.
 Literal Character Constants are all single characters represented
within single quotes like ‘A’, ‘a’, ‘:’, ‘1’, etc.
 Literal String Constants are group of characters represented within
double quotes like “Hello”, “Programming”, “A”, etc.

THE PREPROCESSING ( # )
10
 # is called as the pre-processor symbol.
 The statements which are following the # symbol will get pre-
processed, so they are called as pre-processor directives.
 Pre-Processing is done by the preprocessor which inserts the
files given with the pre-processor symbol # into the actual
program before it gets executed.
 Pre-Processing is done before the actual main program is
compiled by the compiler. Any statements that follow the #
symbol will be embedded as if present in the actual program.

COMPILATION & EXECUTION OF A
C PROGRAM
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 The Source Code files of C are saved with the extension
( *.C ) (where * denotes the file name)
 They are then compiled by the compiler to a Object Code
( *.obj )
 Then the Object Code will be linked by the Linker to form
the Machine Language also known as Executable Code,
files with extension ( *.exe)

COMPILATION & EXECUTION OF A
C PROGRAM
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C Program (with *.C extension)
Preprocessor
Object Code (with *.obj extension)
Executable Code (with *.exe extension)
Compiler
Linker

SYMBOLIC CONSTANTS
13
 The #define statement is used to create Symbolic
Constants known as Macros (replacement text).
 The statement #define PI 3.14 will create PI to have the
constant value 3.14.
 The constant created with #define can be used in
program that will represent the constant value defined for
it.
 It is also used to create Macro Functions or Macros.

HEADER FILES (*.h)
14
 Files with the extension *.h are said to Header Files.
 In a C program many inbuilt functions might be used, those
functions Prototype (Declaration) need to known to compiler which
are already specified in the particular header files related to them.
 The header file like stdio.h is the Standard Input / Output header file
which contains the Prototype or Declaration for all the inbuilt Input /
Output related functions.
 In in C Program different header files might be included in the pre-
processor based on the inbuilt functions used by the program.

The main() Function
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 In every C Program there will be at least one function
without which the program does not execute which is the
main() function.
 The main() Function is the Entry Point for every program
from which the compiler starts to compile the program.
 All the C Programs start to execute from the Open Block
{ where the main() function begins and ends at the Close
Block } where it ends.
 So, the statements or coding written inside the main()
block gets executed at the runtime of the program.

TWO TYPES OF main()
FUNCTION
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#include<stdio.h>
void main()
{
statements;
…….
…….
}
#include<stdio.h>
int main()
{
statements;
…….
return 0;
}
Syntax for a Function or A Function is identified by the following
return_type Function_name(argument_list)
Here the return_type is the value which the function returns back to the area from where it
was invoked. The Function_name is the name given to the function and the () just following
the function name is the identification that it is a function within which arguments passed to
the function will be specified.

DATA TYPES IN ‘C’
Data Types
Primary Data Types
Integers
Floating Points
Characters
Strings
Derived Data Types
Arrays
Pointers
Functions
User-Defined Types
Structures
Unions
Enumerations
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Description Keyword Format String Memory Range
Short Range of
numbers
int %d 2 Bytes -32768 to
+32767
Long Range of
numbers
long %ld 4 Bytes -2147483648
to
+2147483647
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INTEGERS

Single Precision
Decimal numbers
float %f 4 bytes 3.4 e-38 to
3.4e+38
Double Precision
Decimal Numbers
double %lf 8 bytes 1.7e-308 to
1.7e+308
Range of Decimals
beyond double
long double %Lf 10 bytes 3.4e-4932 to
1.1e+4932
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FLOATING POINTS

CHARACTERS
Single Characters char %c 1 Byte -128 to +127
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All the Alphabets, Numbers, Special Symbols represented within
SINGLE QUOTES are said to characters.
For example ‘a’ ‘A’ ‘{‘ ‘:’ ‘1’
All Characters have a unique Number Representation which is called
as the ASCII CODE.
ASCII means American Standard Code for Information Interchange.
For example the ASCII Value for the character ‘A’ is 65 and ‘0’ is 48

THE unsigned DATA TYPE MODIFIER
Description Keyword Format
String
Memory Range
Short Range of
unsigned numbers
unsigned int %u 2 Bytes 0 to 65535
Long Range of
unsigned numbers
unsigned long %u 4 Bytes 0 to
4294967295
Unsigned
Characters
unsigned char %u 1 byte 0 to 255
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Syntax : unsigned <type> <variable> ;
Description : Use the unsigned type modifier when variable
values will always be positive. The unsigned modifier can be
applied to base types int, char, long, and short.
When the base type is omitted from a declaration, int is
assumed.

VARIABLES
22
 Variables are names used to refer the memory location where different
constants are stored.
 It is like a label given to a particular memory location where the values of
constants are stored.
 For example lets see the pictorial memory representation when a value is
stored in memory for a declaration like
char ch;
…..100 101 102 103 104 105 106 107 108 109 110 111 ….
ch
Address of the memory
Variable name
Value at the memory

RULES FOR GIVING VARIABLE
NAMES
23
 It should begin with a alphabet or underscore ( _ )
followed by any combination of alphabets, underscores,
or digits. E.g. int n1;
 Variable names are case-sensitive i.e. uppercase are
different from lower case letter. E.g. int a, A;
 Variable names cannot be a Keyword.
 No Commas or blank spaces are allowed within a
Variable name.
 Length for declaring a variable depends on the complier.

STRINGS
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 Strings are Group of Characters. In C strings are said to be Character Arrays.
 Array is a collection of similar type of elements referred by a single name and
allocated in a contiguous memory locations.
 char Array_name[size]; where char is data type, Array name is the name given to the
array and [] is the subscript or Delimiters of the array within which the size that is the
no. of characters that the array can contain is specified.
 Strings in C are called as NULL TERMINATED CHARACTER ARRAYS. A special
character called as the NULL character ( ‘0’ ) a backslash with a zero is the last
character ending the array which is automatically inserted by the C compiler after the
last character inputed.
 For example char name[10] = “Dennis”;
‘D’ ‘e’ ‘n’ ‘n’ ‘i’ ‘s’ ‘0’
[0] [1] [2] [3] [4] [5] [6] [7] [8] [9]
100 101 102 103 104 105 106 107 108 109
Index of The Array
Element of the array
Address of each
Element of the array

OPERATORS
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 Arithmetic Operators
 Relational Operators
 Logical Operators
 Assignment Operators
 Conditional or Ternary Operator

ARITHEMETIC OPERTORS
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 Addition Operator +
 Subtraction Operator –
 Multiplication Operator *
 Quotient Division Operator /
 Reminder Division or Modulus Operator
%

UNARY OPERATORS
27
UNARY + OPERATOR
 The Operator unary ‘+’
precedes an operand.
 Operand is the value on
which the operator
operates.
 For Example
 If a=5 then +a means 5
 If a=0 then +a means 0
 If a=-4 then +a means -
4
UNARY - OPERATOR
 The Operator unary –
precedes an operand.
 For Example
 If a=5 then –a means -5
 If a=0 then –a means 0
 If a=-4 then –a means 4
 This operator reverses
the sign of the
operand’s value
Operators that act on one operand are referred to as Unary Operators

BINARY OPERATORS
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 The operands of a binary operator are distinguished as the left or right
operand. Together, the operator and its operand is called as an expression.
 For Example addition of two numbers 4+20 results in 24.
 If a=4 and b=6 then a + b will result in 10 where the left side operand and
the right side operand is b.
 The Modulus Operator (%) produces the reminder of dividing the first by the
second operand. For example
19 % 6 evaluates to 1, since 6 goes into 19 three times with a reminder 1.
Note that the both operands must be integer data types when using modulus
operator (%).
Operators that act on two operands are referred to as Binary Operators

RELATIONAL OPERATORS
29
 Less than Operator <
 Less than or equal to Operator <=
 Greater than Operator >
 Greater than or equal to Operator >=
 Equality Operator ==
 Not Equality Operator !=

LOGICAL OPERATORS
30
Logical AND Operator &&
This operator is used to
combine two expressions
into one and check whether
the both the expressions
are true
For example:-
(6<9)&&(4>2) is true
6==6&&4==3 is false
If a=4 and b=4 then
(a>=a) && (b<=b) is true
Logical OR Operator ||
This operator is used to
combine two expressions
into one and check
whether any one of the
expressions are true.
For example:-
(5>8) || (5<2) is false
6==6 || 4==3 is true
If a=4 and b=4 then
(a>a) || (b<=b) is true
C considers 0 as a false value and any non-zero value as a true value

ASSIGNMENT OPERATORS
31
 Normal Assignment =
For e.g. int a=10;
 Addition Assignment +=
For e.g. int a=10,b=10; then a += b
means a = a + b;
 Multiplication Assignment *=
 Subtraction Assignment -=
 Division Assignment /=
 Modulus Assignment %=
Assignment Operators assign value from Right to Left.
That is right side operand value is assigned to the left side operand

UNARY INCREMENT / DECREMENT
OPERATORS (++, --)
32
 C includes two useful operators which is not
generally found in other computer languages.
 These are the increment and decrement
operators, ++ and --
 The operator ++ adds 1 to its operand, and --
subtracts one. In other words,
a = a + 1 is same as ++a or a++ and
a = a – 1 is same as --a or a--

PREFIXING OF ++ OR --
33
The Prefix increment or decrement operators follow
CHANGE-THEN-USE rule i.e. they first change
(increment or decrement) the value of their operand,
then use the new value in evaluating the expression.
For example,
Prefixing of ++ Prefixing of --
int a=10, b;
b = ++a;
Here first a = a + 1 is
done and the new value is
assigned to b. So b will be
11 and a will also be 11
int a=10, b;
b = --a;
Here first a = a - 1 is done
and the new value is
assigned to b. So b will be
9 and a will also be 9

POSTFIXING OF ++ OR --
34
The Postfix increment or decrement operators follow
USE-THEN-CHANGE rule i.e. they first use the value
of their operand in evaluating the expression and then
change (increment / decrement) the operand’s value.
For example,
Postfixing of ++ Postfixing of --
int a=10, b;
b = a++;
Here first a value is assigned
to b and then a = a + 1
increments the value of a. So,
b will be 10 and a will be 11.
int a=10, b;
b = a--;
Here first a value is assigned to
b and then a = a - 1
decrements the value of a. So, b
will be 10 and a will be 9.

CONDITIONAL / TERNARY
OPERATOR
35
C offers a conditional operator ?: that stores a value
depending upon a condition. This operator is ternary i.e.,
it requires three operands. The general form of
conditional operator ?: is as follows:-
expression1 ? expression2 : expression3
If expression1 evaluates to be true i.e. 1, then the value
of the whole expression is the value of expression2,
otherwise the value of the whole expression is the value
of the expression3. For example,
result = marks >=50 ? ‘P’ : ‘F’;
4==9 ? 10 : 25 evaluates to 25 because test expression
4==9 is false.
(a>b ? (a>c ? a : c) : (b>c ? b : c);
In the above statement the expression will be having the
highest value among the three a, b & c.

FORMATTED I / O FUNCTIONS
36
 The function printf() is used to print the formatted output
on the standard output device (monitor). The function
printf() is an inbuilt function which is defined in the header
file stdio.h
 The function scanf() is used to read the formatted input
from the standard input device (keyboard). The function
scanf() is an inbuilt function defined in the header file
stdio.h
 The header file stdio.h should be included in the
preprocessor directive to use the above mentioned
printf() and scanf() functions in the program

THE printf() FUNCTION
37
Syntax : printf(“formatstring”,arg list);
Example statements for showing the use of printf() function
E.g. 1. printf(“Welcome to C Programming”);
E.g. 2. int a=10;
printf(“Value of a = %d”,a);
E.g. 3. int x=10;long y = 200L; float z = 20.5;
printf(“x = %d y = %ld z = %f”,x,y,z);
printf() function always works from Right to Left that is in the above
example from the last the value of z gets printed in the last format
string %f and then value of y gets printed in the place of %ld location
and finally the value of x gets printed in the place of %d location

THE scanf() FUNCTION
38
Syntax : scanf(“formatstring”,arg list);
Example statements for showing the use of scanf() function
E.g. 2. int a;
scanf(“%d”,&a);
E.g. 3. int x; long y; float z;
scanf(“%d%ld%f”,&x,&y,&z);
scanf() function always works from Left to Right that is the first number
inputted will be assigned to x and then the next number inputted will be
assigned to y and the last number inputted will be assigned to z. Here the
& operator which is called as the address of operator is used to mention
the address of the variable where the value is to be stored. Only when
strings are inputted the & operator is not used in the scanf() functions
other than this for all other data types the & operator is a must to be
prefixed before the variable name in the scanf() function.

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