An algorithm is a defined procedure for problem-solving, consisting of logical steps that produce outputs from specified inputs, while flowcharts visually represent these steps in a diagrammatic format. Algorithms and flowcharts each have unique advantages, such as effective communication and structured programming, but also come with limitations like complexity and difficulty in modifications. The document discusses structured programming concepts, the differences between top-down and bottom-up approaches, and provides a comprehensive overview of programming in C language including data types, constants, and memory management.

1. Algorithm
An algorithm is a procedure or formula for solving a problem.
An algorithm is define as a complete , unambiguous , finite number of
logical steps for solving a specified problem.
Algorithms are used for calculation, data processing, and many other
fields.
Each algorithm is a list of well-defined instructions for completing a
task.Starting from an initial state(START), the instructions describe a
computation that proceeds through a well-defined series of successive
states, eventually terminating in a final ending state (STOP).

2. Guidelines for construct an
algorithm
 It should begin with start statement
 Given problem should be broken down into simple
and meaningful steps
 Steps should be numbered sequentially
 Steps should be descriptive and written in simple
English
 Last step should be end statement

3. Eg: Algorithm to average of n numbers
Step 1 : start
Step 2 : Read value of n
Step 3 Read n numbers
Step 4 : add these n numbers
Step 5 : divide the sum by n to get average
Step 6 : print the average
Step 7 : Stop

4. Properties:
Finiteness: - an algorithm terminates after a finite
numbers of steps.
 Definiteness: - each step in algorithm is unambiguous.
This means that the action specified by the step cannot be
interpreted (explain the meaning of) in multiple ways &
can be performed without any confusion.
 Input:- an algorithm accepts zero or more inputs

5. Output:- it produces at least one output.
 Effectiveness:- it consists of basic instructions
that are realizable. This means that the
instructions can be performed by using the given
inputs in a finite amount of time.

6. flowchart
A diagrammatic representation of sequential steps of
solution of problem consisting standard block symbols
being link together by directional arrows are called
flowchart.

7. Basic Flowchart symbols

9. Meaning of flowchart symbols
Symbol name Description
Terminal Indicates the beginning or end of an algorithm
Input/Output The point at which values of some data item have to read or
some results written are indicated by input/output box
Process
Indicates computation or data manipulation
Flow lines Connects the flowchart symbols and indicates the logic flow
Decision Is used to indicate point at which decision has to be made
and branch one/two alternatives possible
Connector Indicates an entry to, or exit from another part of the
flowchart or a connection point

10. Guidelines for constructing a
flowchart
While drawing flowchart Initially concentrate on the
logic of the problem and draw the main path of the
flowchart
Flowchart can have only 1 start point and 1 stop point
Use descriptive term that aptly represent logic of the
problem. Do not use ambiguous terms
Remember that another user/programmer should
easily understand flowchart

11. Example of flowchart
Flowchart for sum of first 50 natural numbers

12. Importance/ benefits of flowcharts
 Communication: Flowcharts are better way of
communicating the logic of a system to all concerned.
 Effective analysis: With the help of flowchart, problem can
be analyzed in more effective way.
 Proper documentation: Program flowcharts serve as a good
program documentation, which is needed for various
purposes.
 Efficient Coding: The flowcharts act as a guide or blueprint
during the systems analysis and program development
phase.

13.  Proper Debugging: The flowchart helps in
debugging process.
 Efficient Program Maintenance: The maintenance
of operating program becomes easy with the help
of flowchart. It helps the programmer to put
efforts more efficiently on that part

14. LIMITATIONS OF USING FLOWCHARTS
 Complex logic: Sometimes, the program logic is
quite complicated. In that case, flowchart becomes
complex and clumsy.
 Alterations and Modifications: If alterations are
required the flowchart may require re-drawing
completely.
 Reproduction: As the flowchart symbols cannot be
typed, reproduction of flowchart becomes a
problem.
 The essentials of what is done can easily be lost in
the technical details of how it is done.

15. Distinguish between algorithm and flow chart
Algorithm Flowchart
Algorithm is a procedure for solving a
problem
Flowchart is a graphical diagram of the
solution to the problem
The algorithm is constructed out of
boxes and it is written as various steps
It is constructed with the shapes of each
box indicating the kind of operation to be
performed.
The actual operation are written in
different steps
The actual operation to be performed is
written inside the symbol
The step numbers shows which step is
to be done next or ‘ go to ‘ statements is
used to specified the next step to be
performed
The arrow coming out of symbol
indicates which operation to perform next

16. Structured programming concept
Structured programming is a concept in which a large program can
be divided in to small modules and can be solved each module one by
one.
Computer programming in which the statements are organized in a
specific manner to minimize error or misinterpretation.
Principles of structured programming are
Structuring of control flow
Decompose a program into portions or modules
Program design using Top down or bottom up approach

17.  Structuring of control flow is to keep the complexity of a program
under control so that design and understanding of a program
logic become easier.
 Three main structures in structured programming are
 Sequence
 Selection
 Repetition
structuring of control flow

18. Sequence logic
It refers to the line-by-line execution. The
program enters the sequence, does each
step, and exits the sequence

19. Selection logic
 In it there are various conditions on the basis of which one module is
selected out of several given modules.

20. Repetition logic
 In it loops are implemented. Loop is used to implement those
statements which are to be repeated again and again until some
condition is satisfied.

21. Modular programming
Modular programming is a programming strategy where a program is
divided into segment called modules.
A module is a unit or entity that is responsible for a single task or routine.
module consisting of series of program instructions or statements in some
programming language
Program using this approach consisting of a main module called control
module and number of functional modules
A module may also decomposed into subordinate modules representing a
sub task.

22.  A module that control subordinate modules is also known as superior
module
 Superior module does not include codes of subordinate modules .
superior module calls subordinate modules for execution
 Subordinate modules also referred as called module and superior
module as calling module.

23. Main/control
module
Functional
module 1
Functional
module n
Subordinate
modules
Superior
module

24. Advantages of modular programming
Modularization has several benefits, especially on large and complex
programs:
 Divide work for multiple programmers.
 Reuse code-modules can be re-used in several projects
changing the implementation details of a modules does not require to
modify the clients using them as far as the interface does not change;
faster re-compilation, as only the modules that have been modified
are actually re-compiled;
self-documenting, as the interface specifies all that we need to know
to use the module;
easier debugging, as modules dependencies are clearly specified and
every module can be tested separately;

25. The program can be solved in two ways they are:
 Top down programming
 Bottom up Programming
Top down and bottom up approach

26. Top-down programming
 Top-down programming is a programming style, in which complex
pieces are divided into smaller pieces. Each pieces are again
divided into sub systems until we get the most simple piece of
program . Then each pieces are solved independently
 Top down approach program design starts with specification of
function to be performed by a program and then breaks it down into
progressively subsidiary functions
 In topdown approach calling module is always designed before the
called module
D
B
A
C
E F G H
Each box in the figure is a module .
Topmost module represented by A.A
Decomposed to B,C,D. B and C further
subdivided to sub components.

27. It initiates human tendancy to solve a problem by outlining broad
concepts first and then subsequently going into detail
Development of module can take place in parallel.
Separating the low level work from the higher level objects leads to a
modular design.
Very less time consuming (Each programmers are involved only a part
of the big project)
Very optimized way of processing. (Each programmers have to apply
their own knowledge and experience to their parts (modules), so our
project will become an optimized one )
Advantages of top-down programming

28. Disadvantages of top-down programming
Top-down programming complicates testing. Noting executable exists
until the very late in the development, so in order to test what has been
done so far, one must write stubs. (Stubs are software programs which
act as a module and give the output as given by an actual
product/software.)
top-down programming tends to generate modules that are very
specific to the application that is being written, thus not very reusable.
The implementation cost is likely to be higher.

29. Bottom-up approach
 Is reverse of topdown approach
 In a bottom-up approach the individual base elements of the system
are first specified in great detail
 These elements are then linked together to form larger subsystems
 In this approach the beginnings are small but eventually grow in
complexity and completeness
A
F
E
B C D
H
G

30. Advantages of Bottom up programming
The advantages of using a bottom-up approach to software testing is the fact that
there is no need for stubs.
bottom-up design yields programs which are smaller and more agile. A shorter
program doesn't have to be divided into so many components, and fewer
components means programs which are easier to read or modify. Fewer
components also means fewer connections between components, and thus less
chance for errors there.
errors in critical modules are found earlier
major functions and processing are tested earlier.
Bottom-up design promotes code re-use.

31. Disadvantages of bottom up programming
A disadvantage of bottom-up design is that it is not focused on specific
requirements. a program designed from the bottom up may not exactly fit
the given problem.
High quality bottom-up solutions prove very hard to construct
Components may be coded without having a clear idea of how they link
to other

32. Difference between topdown and bottom up
programming
Top Down Programming Bottom up programming
Begins the design with main module
progress downward to lowest
modules
Begins the design with lowest level
module progress upward to top level
or main module
Code is not reusable Code is reusable
Testing become complicate Testing become easy compared to top
down

33. Programming
 A program is a sequence of instructions written to perform a
specified task.
 programming is the process of designing, writing, testing,
debugging / troubleshooting, and maintaining the source code of
computer programs.
 source code is a text written in a programming language.

34. Translators
 Translation is the process of converting high level language into low
level language.
 Translators are the programs used to do this translation

Translator
Source code Object code

35. Two types of translators are
 Compilers
 Interpreters
 Computer programs written in any language other than machine
language must be either interpreted or compiled.

36. Compilers
 A compiler is a computer program (or set of programs) that
transforms source code written in high level programming
language into machine language.
 It converts entire program in one go and report all the errors of
the program along with line numbers
 Once object code available compiler is not needed in memory

37. Interpreter
 In computer science, an interpreter is a program which translates
one statement of a high level language program into machine code
and Executes it .
 if there is any error in any line it reports it at the same time and
program execution cannot resume until the error is rectified.
 Interpreter must always present in memory every time program
executed as every time program is run it is first interpreted then
executed
 BASIC and LISP are especially designed to be executed by an
interpreter.

38. Difference Between Compilers and Interpreters
Compiler Interpreter
1.It reads the entire program once and
then translates it before execution.
1.It read one statement at a time and
translate it into machine code, executes it
and then go to the next statement of the
program.
2.Object code is stored after compilation. 2. Object code is not stored.
3.compilation is very fast 3. Whole execution is slow.
4.Errors are displayed after compilation 4. Errors are displayed as and when they
are found and further translation is
possible after correcting it.

39. Introduction to C language

40. C Character Set
A character denotes any alphabet ,digit or symbols to
represent information.
 Numerals: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9
 Alphabets: a, b, ….z, A, B, ……...Z
Arithmetic Operations + - * / %(Mod)
 Special Characters ) ( { } etc

41. C Identifiers
 They are user defined names. They do not have any
predefined meanings
 Identifiers" or "symbols" are the names you supply for
variables, functions, and labels in our program.
 Identifier names must differ in spelling and case from
any keywords.
 You create an identifier by specifying it in the
declaration of a variable, type, or function.
 Eg: sum,total

42. Rules for the identifiers
 You cannot use keywords
 Must not contain white space
 First character must be letter(or underscore)
 Must consist of only letters, digits or underscore

43. C Keywords
 Key words are NOT user defined names
 They have predefined meanings
 These keywords can be used only for their intended
purpose; they cannot be used as programmer-defined
identifiers.
 keywords are all lowercase.
 C makes use of only 32 keywords or reserved words.

44. The standard keywords are
auto extern sizeof
break f l o a t s t a t i c
case f o r s t r u c t
char got0 switch
const i f typedef
continue i n t union
d e f a u l t long unsigned
do r e g i s t e r void
double return v o l a t i l e
else short while
enum signed

45. Data Types
C supports several different types of data, each of
which may be represented differently within the
computer’s memory.
Data types allow programmer to select type of data
appropriate to the needs of the application as well as
the machine.

47. Int type
Figure for Storing the integer 7
using a binary code.
An integer is a number with no fractional part
Integers are stored as binary numbers.

48. Floating Point Types
 Floating point number is a number containing a decimal point and or
an exponent
 Floating point number represents a real number with 6 digits
precision.
 Floating point numbers are denoted by the keyword float.
 Some floating-point numbers are 2.75, 3.16E7, 7.00, and
 2e–8.
 When the accuracy of the floating point number is insufficient, we
can use the double to define the number.
 The double is same as float but with longer precision(14 digits
precision)

49. Float and double storage
 Floating-point representation involves breaking up a number into a
fractional part (mantissa) and an exponent part and storing the parts
separately
IEEE format for floating point storage use sign bit, mantissa and exponent.
Sign bit denotes sign of a number .0 for positive value 1 for negative value
mantissa is represented in binary
Exponent is an integer stored in unsigned binary format after adding a
positive integer bias. This ensures that the stored exponent is always positive.
Value of bias is 127 for floats and 1023 for double
IEEE format for floating point storage

50.  A single-precision binary floating-point number is stored in 32 bits
 Storing the number 0.15625 in 32 bit representation is shown below
In IEEE format ,value=
sign = the sign bit. (0 makes the number positive ; 1 makes it
negative.)
exp = the 8-bit number stored in the exponent field. exp = biased
exponent = the true exponent + 127.
fraction (mantissa)= the 23 bits of the fraction field.

51.  In the example, the sign is 0, so the number is
positive;
 exp is 124, so the true exponent is –3;
 and fraction is .01. So, the represented number is:

52. value=(-1)sign
*1.fraction*(2exp-1023)
Exponent =true exponent +1023
IEEE format for Double storage
double precision is essentially the same except that the fields are
wider.
The fraction part is much larger, while the exponent is only slightly
larger.

53. Character Type
 A single character can be defined as a character(char) type of
data.
 Characters are usually stored in 1 byte of internal storage.

54. Void Type
 Void type has no values
 Used to specify type of function
 Type of function is said to be void when it does not return any
values to the calling function

55.  The qualifiers define the amount of storage allocated to
the variable.
4 data type qualifiers are available in c
 short
 long
 signed
Unsigned
size qualifiers- Short and long
Sign qualifiers-Signed and unsigned
Points to be noted
All of these modifiers can be applied to base type int
Signed and unsigned can be apply to base type char
Long can be apply for double
When basetype omitted from declaration int is assumed
Data type qualifiers(data type modifiers)

56. A short int may require less memory than an ordinary int or it may
require the same amount of memory as an ordinary int , but it will never
exceed an ordinary int in word length.
a long int may require the same amount of memory as an ordinary int or it
may require more memory, but it will never be less than an ordinary int.
A signed integer use one bit for storing sign and rest 15 bits for
number. Sign bit is 0 for positive number and 1 for negative
Unsigned numbers are always positive and consume all the bits for the
magnitude of the number

57. Size and range of data types on a 16 bit machine

58. CONSTANTS
 constant refer to fixed values that do not change
during execution of a program.

59. Integer and floating-point constants represent numbers. They are
often referred to collectively as numeric-type constants.
1. Commas and blank spaces cannot be included within the constant.
2. The constant can be preceded by a minus (-) sign if desired.
3. The value of a constant cannot exceed specified minimum and maximum bounds.
rules apply to all numeric-type constants.

60. 1. Integer Constants:
 An integer constant is an integer-valued number. it consists of a
sequence of digits .
 C allows 3 types of integer constants
decimal (base 10 )
octal (base 8)
hexadecimal (base 16).

61. (i) Decimal Integer Constant:
A decimal integer constant can consist of any combination of
digits taken from the set 0 through 9 preceded by optional – or +
sign.
If the constant contains two or more digits, the first digit must be
something other than 0.
Several valid decimal integer constants are shown below.
743 5280 32760 9999

62. (ii) Octal Integer Constant:
An octal integer constant can consist of any combination of digits taken
from the set 0 through 7.
first digit must be 0,in order to identify the constant as an octal number.
Eg.: 01 ,0743 ,0551

63. (iii) Hexadecimal Integer:
A hexadecimal integer constant must begin with either ox or 0X.
It can then be followed by any combination of digits taken from the sets 0
through 9 and a through f (either upper- or lowercase).
the letters a through f (or A through F) represent the decimal quantities 10
through 15, respectively
E.g: 0x2,, 0X7FFF, 0xbcd

64. Floating point Constant(Real constants)
 A floating-point constant is a base 10 number that contains either a
decimal point or an exponent (or both).
 floating point constants can be expressed in two forms
 Decimal notation
 Exponential notation

65.  A floating point constant in decimal notation Having whole number
followed by decimal point and fractional part with optional + or –
sign.
 Examples +867.9, -26.9876

66. In exponential form, the real constant is represented as two parts.
General form of floating point constant in exponential form is
mantissa e exponent
 The part before the ‘e’ is the ‘mantissa’, and the one following ‘e’ is the
‘exponent’.
Mantissa is either a real number expressed in decimal notation or an
integer.
Exponent is an integer number with optional plus or minus sign.
 1.6667E+8, 0.006e-3

67. Single Character constant
A character constant is a single character, enclosed in single
quotation marks.
Eg: ’B’, ’?’, ’3’
Character constants have integer values known as ASCII
values(example ‘A’ have the value 65)

68. Escape Sequences
Certain nonprinting characters as well as the backslash() and
apostrophe(‘),can be expressed in terms of escape sequences.
An escape sequence always begins with a backward slash and is
followed by one or more special characters.

69. The commonly used escape sequences are listed below.

70.  a is used to give an audible alert or beep sound.
 b is used to delete one character to the left of cursor , equivalent to
backspace.
 f is used for form feed , or to feed a blank page when printing
documents.
 t is used for horizontal tab , or to move the cursor to next tab stop
position.
 n is used to go to the start of next line
 v is used to Go to the start of the line at the next vertical tab
position.
 r is used for carriage return , or Go back to the start of the current
line.
 is used to print a backslash.
 ’ Is used to print a single quote.
 ” is used to print a double quote.

71. null character 0
The escape sequence 0. This represents the null character
(ASCII OOO), which is used to indicate the end of a string .
Note that the null character constant 0 is not equivalent
to the character constant ‘0’ .

72. String Constants
A string constant is a sequence of characters enclosed in double
quotation marks.
Eg: "green" "Washington, D.C. 20005H “ “270-32-3456“

73. C Variables
 A variable is an identifier that is used to represent a single data item; i.e a
numerical quantity or a character constant.
 A variable may take different values at different times during the execution.
However datatype associated with the variable cannot change.
 It is a good practice to choice a meaningful variable names.
 For example average , total

74. Rules for Constructing Variable Names
1. They must begin with a letter or underscore.
2. the maximum allowable length of a variable name is 31
characters. However length should not be normally more than
8 characters.
3. Uppercase and lowercase are significant. That is, the
variable Amount is not the same as amount or AMOUNT.
4. It should not be a keyword.
5. White space is not allowed.

75. ARRAYS
An array is an identifier that refers to a collection of data items that all
have the same name.
 The data items must all be of the same type (e.g., all integers, all
characters, etc.).
The individual data items are represented by their corresponding array-
elements

76. The individual array elements are distinguished from one another by the
value that is assigned to a subscript or index .
The subscript associated with each element in an array is shown in
square braces.
Value of subscript for first element is 0,second element is 1 and so on.
For example
A is 5 element array.
First element referred by A[0],second by A[1],last element by A[4]

77. For an n-element array, the subscripts will range from 0 to n-1
 Note that an n-character string will require an (n+1 ) element
array, because of the null character (0) that is automatically
placed at the end of the string.

78. Suppose that the string "California" is to be stored in a one-dimensional character array
called l e t t e r .
" C a l i f o r n i a " contains 10 characters, letter will be an 11-element array.

79. DECLARATIONS
A declaration associates a group of variables with a specific data
type.
 All variables must be declared before they can appear in executable
statements.
A declaration consists of a data type, followed by one or more
variable names, ending with a semicolon.
datatype v1, v2, v3….vn;
V1,v2,…are variable names
Each array variable must be followed by a pair of square brackets,
containing a positive integer which specifies the size (i.e., the number of
elements) of the array.

80. example of type declarations
i n t a, b ;
f l o a t ro ot ;
char f l a g , t e x t [ 8 0 ] ;
a and b are declared to be integer variables
root is a floating-point variable
f l a g is a char-type variable and
t e x t is an 80-element, char-type array.
We can use type qualifiers in variable declaration like short int
a, b

81. Intial values of variables can be assigned to variables within type
declaration.
Then declaration must consist of a data type, followed by a variable
name, an equal sign (=) and a constant of the appropriate type.
For examples
i n t c = 12;
char star = " * ”;

82. Expressions
 An expression represents a single data item, such as a number or a
character.
 The expression may consist of a single entity, such as a constant, a
variable, an array element or a reference to a function.
 It may also consist of some combination of such entities,
interconnected by one or more operators.
 Expressions can also represent logical conditions that are either true
or false. in C the conditions true and false are represented by the
integer values 1 and 0 ,respectively
 Expressions in C are basically operators acting on operands.
 In C every expression evaluates to a value i.e., every expression
results in some value of a certain type that can be assigned to a
variable.

83. Examples of expression
a + b represents sum of values of a and b
x = y Value represented by y to be assigned to
x
c = a + b represents sum of values of a and b is
assigned to variable c
x <= y Will have value true if x is less than or
equal to the value of y otherwise
expression will have value 0
Expression meaning

84. A statement causes the computer to carry out some action.
There are three different classes of statements in C.
 expression statements,
 compound statements
 control statements

85. An expression statement consists of an expression followed by a
semicolon;
 The execution of an expression statement causes the expression to be
evaluated.
Example of expression statement c=a+b;
Expression statement

86. compound statement
A compound statement consists of several individual statements enclosed
within a pair of braces { }.
The individual statements may themselves be expression statements,
compound statements or control statements.
Unlike an expression statement, a compound statement does not end with a
semicolon.
Example of compound statement
{
p i = 3.141593;
area = p i * radius * radius;
} This compound statement consists of 2 expression statements

87. Control statements
Control statements are used to create special program
features, such as logical tests, loops and branches

88. L-Value and R-Value
 There are 2 values with a variable
 Its location value(L value) that is the address in memory at which its
data value is stored.
 Its data value stored at some location in memory referred to as r
value.
Rvalue of A=10 Rvalue of C=25
Lvalue of A=1052 Lvalue of C=1054

89. Lvalue is an expression to which you can assign a value.
 L value and R value refer to on the left and right side of the assignment
operator.
 The Lvalue concept refers to the requirement that the operand on the left
side of the assignment operator is modifiable, usually a variable.
 l-values can be made nonmodifiable by using the const keyword;
Rvalue concept pulls or fetches the value of the expression or operand on
the right side of the assignment operator.
l-values are r-values but not all r-values are l-values.

90. consider a=b;
b,on the right hand of assignment operator is the quantity to be found at
the address associated with b i.e an rvalue
a ,on the left hand side is assigned an value stored in the address
associated with b so a is an lvalue
Assignment operation deposits b’s rvalue at a’s lvalue

91. SYMBOLIC CONSTANTS
A symbolic constant is a name that substitutes for a sequence of characters.
a symbolic constant allows a name to appear in place of a numeric constant,
a character constant or a string. When a program is compiled, each occurrence
of a symbolic constant is replaced by its corresponding character sequence.
Symbolic constants are usually defined at the beginning of a program.

92. General format of symbolic constant is
#define name text
Name symbolic name typically written in uppercase letters
Text represents sequence of characters that is associated with the
symbolic name.
Text does not end with a semicolon
example
#define PI 3.141593

93. the symbolic names are written in uppercase, to distinguish
them from ordinary C identifiers.
It is much easier to change the value of a single symbolic
constant than to change every occurrence of some numerical
constant that may appear in several places within the program.