Baabtra.com little coder chapter - 2

Little Coder Program

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What you’ve learned?

What is instructions?

How to give instructions sequentially to accomplish a task !

What is Computer programming ?

What are computer languages?

Start with PythonChapter 2

Python

– Python is a computer language which is very easy

to learn and can be used to give instructions to a

computer

Setting up python environment in Windows

1. Goto http://www.python.org/ and download the latest

Windows installer

2. for Python 3. Look for a section in the menu titled Quick

Links,

3. The exact version of Python that you download is not

important, as long as it starts with the number 3.

4. After you download the Windows installer, double-click its icon,

and then follow the instructions to install Python in the default

location, as follows:

i. Select Install for All Users, and then click Next.

ii. Leave the default directory unchanged, but note the name of the

installation directory (probably C:\Python31 or C:\Python32).

Click Next.

iii. Ignore the Customize Python section of the installation, and

click Next.

• At the end of this process, you should have a Python 3 entry in

your Start menu:

Setting up the environment in MAC

1. Go to http://www.python.org/getit/ and download the latest installer for

MAC

i. If you’re running a Mac OS X version between 10.3 and 10.6, download the 32-

bit version of Python 3 for i386/PPC.

ii. If you’re running Mac OS X version 10.6 or higher, download the 64-bit/32-bit

version of Python 3 for x86-64.

2. Once the file has downloaded (it will have the filename extension.dmg),

double-click it. You’ll see the file as shown below

3. In this window, double-click Python.mpkg, and then follow the

instructions to install the software

http://www.python.org/getit/

Setting up the environment in Ubuntu

1. Python comes preinstalled on the Ubuntu Linux distribution, but it may

be an older version. Follow these steps to install Python 3 on Ubuntu 12.x:

2. Click the button for the Ubuntu Software Center in the Sidebar(it’s the

icon that looks like an orange bag—if you don’t see it, you can always

click the Dash Home icon and enter Software in the dialog).

3. Enter Python in the search box in the top-right corner of the Software

Center.

4. In the list of software presented, select the latest version of IDLE, which is

IDLE (using Python 3.2) in this example:

5. Click Install.

6. Enter your administrator password to install the software, and then click

Authenticate.

Let’s do programming in python


• Opening Python console !

– Once you install python, You should have an icon on your Windows or Mac OS X

desktop labeled IDLE. If you’re using Ubuntu, in the Applications menu, you

should see a new group named Programming with the application IDLE Double-

click the icon or choose the menu option, and you should see this window:


• This is the play ground where we give instructions to the

computer to accomplish our tasks. Sooner you will learn about

what all instructions we can give

Python Commands

• In this chapter you we will learn 3 instructions

or commands

– To print a message to computer screen

– To do arithmetic calculations

– To store values into computer memory

Print() Command

• Type below in your console and press enter

>>> print("Hello baabtra, You are awesome")


Hello baabtra, You are awesome

>>>

Print() Command

• Type below in your console and press enter



Hello baabtra, You are awesome

>>>

Congratulations! You’ve just created your first Python program.The word print is a type of Python command called a function, and it prints out whatever is inside the parentheses to the screen. In essence, you have given the computer an instruction to display the words “Hello baabtra, You are aswesome”

Try This !

• Write python command to

–Print your name

–Print Your Age

–Print your hobbies

Saving your file

1. To save a new program, open IDLE and choose File => New

Window.

2. An empty window will appear, with *Untitled* in the menu bar.

3. Enter the following code into the new shell window:

print("Hello World")

4. Now, choose File=>Save. When prompted for a filename, enter

hello.py, and save the file to your desktop.

5. Then choose Run=>RunModule.

Python Operators

Python Operators

+ Addition

- Subtraction

* Multiplication

/ Division

Python Operators

>>>8 * 3.57

Type this an press enter in your python console

>>> 17 + 365

>>>8 * 3.57

28.56

>>> 17 + 365

382

>>> 174 - 36>>> 174 - 36

138

>>> 324 / 36>>> 324 / 36

9

Try This !

• Write python command to find the result of

– 1340+ 1242- 43*4

–(123-12)*12+14

–12*(16/2)+13*2

Variables

Variables

• You already know that our computers are having memory to store

things !We can make use of this memory in our program to store

values using something called variables

• The word variable in programming describes a place to store

information such as numbers, text, lists of numbers and text, and

so on.

Creating a variable

• In order to create a variable named ‘studentid’ with value 100,

Type as below and press enter

>>> studentid=100

Creating a variable

• In order to create a variable named ‘studentid’ with value 100,

Type as below and press enter

>>> studentid=100

When you entered studentid=100, the computer

reserved one of the memory for us and assigned a name

‘studentid’ and stored the value 100 inside it.

How to print the value of variable

• To print the value of a variable you can simply give it inside

print() function

>>>print(studentid)

100

>>>studentName=“John”

>>>print(studentName)

John

Printing variable value inside a message

• Suppose if you want to a message as below

“Hello friends, My name is John and my Id is 100”

• It can be done as of below

>>print(“Hello friends,My name is %s and my Id is %d”% (studentName,studentId))






Here %s will be substituted with the value of variable

studentName






Here %d will be substituted with the value of variable studentid

What is this %s and %d ?

• %s is used as a placeholder for string values you want inject into a

formatted string.

• %d is used as a placeholder for numeric or decimal values.

Type this and press enter in your python console

Now print the below message using print() function

“ Yahoo, I’ve got 45 marks out of 50 in Maths

subject !”

Try this

>>>subjectName=“Maths”

>>>totalMark=50

>>>myMark=45


Now print the below message using print() function

“ Yahoo, I’ve got 45 marks out of 50 in Maths

subject !”

Try this


>>>totalMark=50

>>>myMark=45 Answer

>>>print(“ Yahoo, I’ve got %d marks out of %d in %s subject !

%myMark,totalMark,subjectName)


Now calculate your percentage of mark and print the below message

“Hey, I’ve got 90 percentage of mark in Maths”

Try this


>>>totalMark=50

>>>myMark=45


Now calculate your percentage of mark and print the below message

“Hey, I’ve got 90 percentage of mark in Maths”

Try this


>>>totalMark=50

>>>myMark=45

Answer>>>percentage=myMark/totalMark

>>>print( “Hey, I’ve got %d percentage of mark in %s”%percentage,subject”)

Exercise !

Exercise• John has 19 apples, 21 oranges and 14 bananas to sell

• Write a python program to

• Print the total number of fruits John has?

• If he sell 12 apples, 9 oranges and 14 bananas, print how

many fruit will be left with him?

apple=19

orange=21

banana=14

totalFruits=apple+orange+banana

print(“Total Fruits = %d”% totalFruits)

apple=apple-12

orange=orange-9

banana=banana-14

totalFruits=apple+orange+banana

print(“Total Fruits after selling = %d”% totalFruits)

End of Chapter 2