notes on Programming fundamentals

Notes on
Concepts of Programming
Instructor:
Arghodeep Paul
Firmware Engineer at BitBible Technologies Pvt. Ltd.
Content License Under: OpenSource
Date: 05 July 2021

Computer programming is the act of writing computer programs, which are a
sequence of instructions written using a Computer Programming Language to
perform a specified task by the computer.
Introduction to Computer Program
Before getting into computer programming, let us first understand computer
programs and what they do.
A computer program is a sequence of instructions written using a Computer
Programming Language to perform a specified task by the computer.
The two important terms that we have used in the above definition are −
 Sequence of instructions
 Computer Programming Language
To understand these terms, consider a situation when someone asks you about how
to go to a nearby KFC. What exactly do you do to tell him the way to go to KFC?
You will use Human Language to tell the way to go to KFC, something as follows −
First go straight, after half kilometer, take left from the red light and
then drive around one kilometer and you will find KFC at the right.
Here, you have used English Language to give several steps to be taken to reach KFC.
If they are followed in the following sequence, then you will reach KFC −
1. Go straight
2. Drive half kilometer
3. Take left
4. Drive around one kilometer
5. Search for KFC at your right side

Now, try to map the situation with a computer program. The above sequence of
instructions is actually a Human Program written in English Language, which
instructs on how to reach KFC from a given starting point. This same sequence could
have been given in Spanish, Hindi, Arabic, or any other human language, provided
the person seeking direction knows any of these languages.
Now, let's go back and try to understand a computer program, which is a sequence
of instructions written in a Computer Language to perform a specified task by the
computer. Following is a simple program written in Python programming Language
−
print "Hello, World!"
The above computer program instructs the computer to print "Hello, World!" on
the computer screen.
A computer program is also called a computer software, which can range
from two lines to millions of lines of instructions.
Computer program instructions are also called program source code
and computer programming is also called program coding.
A computer without a computer program is just a dump box; it is programs
that make computers active.
As we have developed so many languages to communicate among ourselves,
computer scientists have developed several computer-programming languages to
provide instructions to the computer (i.e., to write computer programs). We will see
several computer programming languages in the subsequent chapters.

Introduction to Computer
Programming
If you understood what a computer program is, then we will say: the act of writing
computer programs is called computer programming.
As we mentioned earlier, there are hundreds of programming languages, which can
be used to write computer programs and following are a few of them −
 Java
 C
 C++
 Python
 PHP
 Perl
 Ruby
Uses of Computer Programs
Today computer programs are being used in almost every field, household,
agriculture, medical, entertainment, defense, communication, etc. Listed below are
a few applications of computer programs −
 MS Word, MS Excel, Adobe Photoshop, Internet Explorer, Chrome, etc., are
examples of computer programs.
 Computer programs are being used to develop graphics and special effects in
movie making.
 Computer programs are being used to perform Ultrasounds, X-Rays, and other
medical examinations.
 Computer programs are being used in our mobile phones for SMS, Chat, and
voice communication.

Computer Programmer
Someone who can write computer programs or in other words, someone who can
do computer programming is called a Computer Programmer.
Based on computer programming language expertise, we can name a computer
programmers as follows −
 C Programmer
 C++ Programmer
 Java Programmer
 Python Programmer
 PHP Programmer
 Perl Programmer
 Ruby Programmer
Algorithm, Pseudocode and Program
Algorithm : Systematic logical approach which is a well-defined, step-by-step
procedure that allows a computer to solve a problem.
Pseudocode : It is a simpler version of a programming code in plain English which
uses short phrases to write code for a program before it is implemented in a specific
programming language.
Program : It is exact code written for problem following all the rules of the
programming language.

Algorithm
An algorithm is used to provide a solution to a particular problem in form of well-
defined steps. Whenever you use a computer to solve a particular problem, the
steps which lead to the solution should be properly communicated to the computer.
While executing an algorithm on a computer, several operations such as additions
and subtractions are combined to perform more complex mathematical operations.
Algorithms can be expressed using natural language, flowcharts, etc.
Let’s take a look at an example for a better understanding. As a programmer, we are
all aware of the Linear Search program.
Algorithm of linear search :
1. Start from the leftmost element of arr[] and
one by one compare x with each element of arr[].
2. If x matches with an element, return the index.
3. If x doesn’t match with any of elements, return -1.
Here, we can see how the steps of a linear search program are explained in a simple,
English language.

Pseudocode
It is one of the methods which can be used to represent an algorithm for a program.
It does not have a specific syntax like any of the programming languages and thus
cannot be executed on a computer. There are several formats which are used to
write pseudo-codes and most of them take down the structures from languages such
as C, Lisp, FORTRAN, etc.
Many time algorithms are presented using pseudocode since they can be read and
understood by programmers who are familiar with different programming languages.
Pseudocode allows you to include several control structures such as While, If-then-
else, Repeat-until, for and case, which is present in many high-level languages.
Note: Pseudocode is not an actual programming language.
Peudocode for Linear Search :
FUNCTION linearSearch(list, searchTerm):
FOR index FROM 0 -> length(list):
IF list[index] == searchTerm THEN
RETURN index
ENDIF
ENDLOOP
RETURN -1
END FUNCTION

In here, we haven’t used any specific programming language but wrote the steps
of a linear search in a simpler form which can be further modified into a proper
program.
Program
A program is a set of instructions for the computer to follow. The machine can’t read
a program directly, because it only understands machine code. But you can write
stuff in a computer language, and then a compiler or interpreter can make it
understandable to the computer.
Program for Linear Search :
// C++ code for linearly search x in arr[]. If x
// is present then return its location, otherwise
// return -1
int search(int arr[], int n, int x)
{
int i;
for (i = 0; i < n; i++)
if (arr[i] == x)
return i;
return -1;
}
Algorithm vs Psuedocode vs Program
1. An algorithm is defined as a well-defined sequence of steps that provides
a solution for a given problem, whereas a pseudocode is one of the methods
that can be used to represent an algorithm.
2. While algorithms are generally written in a natural language or plain
English language, pseudocode is written in a format that is similar to the
structure of a high-level programming language. Program on the other hand
allows us to write a code in a particular programming language.
So, as depicted above you can clearly see how the algorithm is used to generate
the pseudocode which is further expanded by following a particular syntax of a
programming language to create the code of the program.

Elements of PLs
We assume you are well aware of English Language, which is a well-known Human
Interface Language. English has a predefined grammar, which needs to be followed
to write English statements in a correct way. Likewise, most of the Human Interface
Languages (Hindi, English, Spanish, French, etc.) are made of several elements like
verbs, nouns, adjectives, adverbs, propositions, and conjunctions, etc.
Similar to Human Interface Languages, Computer Programming Languages are also
made of several elements. We will take you through the basics of those elements
and make you comfortable to use them in various programming languages. These
basic elements include −
 Programming Environment
 Basic Syntax
 Data Types
 Variables
 Keywords
 Basic Operators
 Decision Making
 Loops
 Numbers
 Characters
 Arrays
 Strings
 Functions
 File I/O
We will explain all these elements in subsequent chapters with examples using
different programming languages. First, we will try to understand the meaning of all
these terms in general and then, we will see how these terms can be used in
different programming languages.
This tutorial has been designed to give you an idea about the following most
popular programming languages −

 C Programming
 Java Programming
 Python Programming
A major part of the tutorial has been explained by taking C as programming
language and then we have shown how similar concepts work in Java and Python.
So after completion of this tutorial, you will be quite familiar with these popular
programming languages.
Programming Environment
Environment Setup is not an element of any Programming Language, it is the first
step to be followed before setting on to write a program.
When we say Environment Setup, it simply implies a base on top of which we can
do our programming. Thus, we need to have the required software setup, i.e.,
installation on our PC which will be used to write computer programs, compile, and
execute them.
A programming environments is the collection of tools used in the development of
software.
This collection may consist:-
 A file system,
 A text editor,
 A linker,
 A compiler,
 Integrated tools
These tools may be access through a uniform interface (GUI).
Some of the examples of programming environments are-
1) Microsoft Visual Studio .NET, which is a large collection of software development
tools, used through a windows interface.
It is used to develop software in following languages-
 C#,
 Visual Basic .NET,
 JScript(MS JavaScript version),
 J# (MS Java version),

 managed C++.
2) NetBeans
3) Turbo C, C++
4) Dreamweaver
5) Arduino, etc.

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