1. Algorithms and flow charts
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Programming language
Programming language is an artificial language that specifies instruction to be executed on a computer. There are two types of programming languages:
Low level languages
High level languages
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Low level languages
A language that is machine-dependent and/or that offers few control instructions and data types. Each statement in a program written in a low-level language usually corresponds to one machine instruction.
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Computer Languages:
The language which consists of a set of commands, understandable by computer directly or after translating, is known as computer programming language.
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Computer Languages:
There are many types of computer languages, which can be categorized into the following four types:-
Low-Level Languages (1st & 2nd Generation Languages)
High-Level Languages (3rd Generation Languages)
User-Friendly Languages (4th Generation Languages)
Object-Oriented Languages (5th Generation Languages)
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Computer Languages:
Low-Level Language:
Languages, which computer can understand directly and are machine dependent are called Low-Level Languages.
For Example:
Machine Language & Assembly Language.
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Computer Languages:
High-Level Language:
The languages, which computer cannot understand directly and are not machine dependent are called High-Level Languages. Some of the high-level languages are:-
BASIC (Beginners All Purpose Symbolic Instruction Code)
COBOL (Common Business Oriented Language)
FORTRAN (Formula Translator)
C etc.
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Computer Languages:
User-Friendly Languages:
These languages are very easy to codify and simplest to learn. Some of the common user-friendly languages are:-
dBASE
FoxPro
Oracle
MS Access
Sybase etc.
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Computer Languages:
Object-Oriented Languages:
The languages which are based on object oriented programming (OOP) approach are called as Object-Oriented languages. For example:-
Smalltalk
C++
Object COBOL
JAVA
Simula etc.
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10. Language Translators:
The software, which converts the codes of other languages into machine code are called Language Translator.
Language Translators are categorized into three types:-
Assemblers
Interpreters
Compilers
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11. Language Translators:
Assembler:
Assembler translates the assembly language code (source program) into machine language code (object program). After assembling, a linker program is used to convert the object program into an executable program. The Microsoft assembler program (MASM) & Borland Turbo assembler program (TASM) are two popular assemblers. Assemblers are used mainly in development of system software.
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12. Language Translators:
Interpreters:
Interpreters translate the high-level language code into machine language code, command by command. They are very slow for executing large programs, so interpreters are not suitable for most of applications development.
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13. Language Translators:
Compilers:
As contrast to interpreters, compilers provide faster execution speed. Compilers translate the entire program (source code) into machine code (object code). By using linker, the object code is converted into executable code. Compilers are widely used in translating codes of high level languages. As compared to assemblers or interpreters, compilers are preferred in development of application software.
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14. Main operation of high level language program
Input operations:
Like input, read
Output operations;
Like write, print
Arithmetic operations:
Like add, subtract, multiply etc....
control transferring operations:
Like “GO TO”, conditional, non-conditional etc....
Looping:
Like repeat, do while, for, etc... 4
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15. Main step in developing program
Problem understanding
Algorithm developing
Program writing
Program editing
Program compiling
Program running
Testing and debugging
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What an Algorithm is ???
“Sequence of precise instructions which leads to a solution
is called an algorithm.” or
“An algorithm is a set of steps that defines how a task is to
performed.”
Example:
Steps (algorithm) for preparing a cake.
Steps (algorithm) to solve a first degree equation.
Steps (algorithm) to solve a second degree equation
using delta.
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Example:
What is algorithm for solving a first degree equation?
1. Read the values A,B
2. Check if A=0 (if yes there is no equation) therefore no
equation to be solved (end processing).
3. Check if B=0 (if yes X=0 and end processing).
4. Calculate the value of X= -B/A
5. Print the value of : X
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Algorithm Representation
There are many ways in which we may represent an algorithm;
We use many techniques to represent an algorithm in computer
programming. The techniques that will study are:
Flowchart
Pseudocde
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Why Flowcharts:
The flowchart is graphical representation of the steps
required for an algorithm or program.
The flowchart is characterized by:
Clarify the program logic
Identify alternative processing methods
Serve as guide for program coding
Serve as documentation
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Principals of Flowchart
1. Simplicity:
Easy to put on paper
Easy to draw
Readable and meaningful
2. Organization:
- putting ideas together and organizing those ideas in logical way.
3. Planning:
- flowchart helps for looking the program in deeper and global way.
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General Concepts
Flowchart must be characterized by the following:
The major element of the project.
Elements are clearly labeled.
Sequence of element must be clear.
No gap or dead ends.
Sequence of elements must be in logical form.
Flowchart must be used correctly.
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Levels of Program Flowchart
Simple sequential flowchart.
Branched flowchart.
Simple-loop flowchart.
Multi-loop flowchart.
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23. No Name Symbol Usage 1 Ellipse Start/Stop 2 Rectangle Expressions 3
Parallelogram
Input (Read) / Output(Print) 4
Rhombus
Conditional checking 5
Arrow
Flow of solution 6
Circle
Connector 7
Elongated Hexagon
Continue 8
Rectangle with bars
Procedure / Function call

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Example:1 Algorithm for reading student name
Start
Read student name
End
start
Read student name
Stop
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Example:2 Algorithm for calculate the area of circle
start
Start
Read value of R
Set PI equal to 3.14
Calculate Area=PI*R*R
Print R, Area
Stop
Read R
PI=3.14
Area=Pi*R*R
Print R, Area
Stop
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Example:3 Draw flow chart for evaluating the following
functions: F(X)=x if X>=0, F(X)= -X if X<0
start
Start
Read X
If X>=0 then go to step 4, else step 5
Calculate F(X)=X than go to step 6
Calculate F(X)=X
Print X, F(X)
Stop
Read X
X>=0
Yes No
F(x)= -x
F(x)=x A
Print x, F(x)
Stop
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Example:4 Write an algorithm and draw the flow chart to add two
numbers.
Algorithm:
Start
Read a, b
Calculate c=a + b
Print c
Stop
Flow chart:
Start
c = a+ b
Print c
Read a, b
Stop
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Exercise 5: Write an algorithm and draw the flow chart to find the circumference of circle
Algorithm:
Start
Read r
Calculate c= 2*3.14 * r
Print c
Stop
Start
c =2 * 3.14 * r
Print c
Read r
Stop
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Flowchart Levels
First Level of Flowchart
It is simplest level which contain the sequence of steps without loops or branch and the flowchart comes in straight line from the beginning to the end.
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Second Level of Flowchart
It is branched flowchart, when there is a condition statement in the program.
Look at the following example:
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Third Level of Flowchart
It is a flowchart which contain iteration or repetitions. It is
usually called loop flowcharts.
In this type we need to repeat some operation several times
using the same set of operation.
The general from for this type is as follows:
condition No
Yes
operation
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Exercise 6: write an algorithm and draw a flowchart for printing 10 integers starting from 1
Algorithm:
Start
Take the initial value of A=1
Check if A>=10 if yes and
If no print the number and increment A by 1
start
End
Print A
A>=10?
A=A+1
A=1
Yes No
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Looping
When we need to use a loop a special symbol can be used
Loop
i = 0,N,M
Instructions to be executed M
Counter i
Any Initial value
Final Value (N)
Increment or Decrement Value (M)
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Homework
Write an algorithm and draw a flowchart to calculate and print the sum of numbers from 1 to 100 .
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