Lecture 1-Intro to programming and python.pdf

March, 2023 – AUT
www.aut.edu
Programming
Python

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© AUT – www.aut.edu
Python and Game design
Workshop
Dr. Kamil KLAIME

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 The workshop will cover the following topics during 4 sessions:
1. Programming Concept (session 1)
2. Programming Languages-Python (session 1)
3. Numbers and variables in python (session 1)
4. Conditions and loops (session 2)
5. Games design under python using Pygame library
(session 3)
6. Introduction to Unity 3D (session 4)
Content

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FROM OEA to AUT-North

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What Is a Program?
 Usually, one or more algorithms written in a programming language that
can be translated to run on a real machine
 We sometimes call programs software

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What Is a Programming Language?
 A programming language is somewhat like a
natural language, but with a very limited set of
statements and strict syntax rules.
 Has statements to implement sequential,
conditional and iterative processing - algorithms
 Examples: FORTRAN, COBOL, Lisp, Basic,
Pascal, C, C++, Java, C#, Python, …

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Compiler
 A compiler is a program that converts a program written in a
programming language into a program in the native language, called
machine language, of the machine that is to execute the program.

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From Algorithms to Hardware (with compiler)
Algorithm
Program
A real computer
Translate (by a human being)
Translate (by compiler program)

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The Program Development Process (Control
Flow)
Edit
Compile
Run
Syntax errors
Input Output
Runtime errors

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Three kinds of errors
 Syntax error : Some statement in the program is not a legal statement
in the language.
 Runtime error : An error occurs while the program is executing,
causing the program to terminate (divide by zero, etc.)
 Logic error : The program executes to completion, but gives incorrect
results.

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Interpreter
 An alternative to a compiler is a program called an interpreter. Rather
than convert our program to the language of the computer, the
interpreter takes our program one statement at a time and executes a
corresponding set of machine instructions.

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Interpreter
Edit
Interpreter
Syntax or runtime errors
Input
Output

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Python
 Python is a real-world, production language that is freely
available for most computers.
http:www.python.org
 you can run and execute python online or on your machine
using many platform, ex : Thonny

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Python online
https://pynative.com/online-python-code-editor-to-execute-python-code/

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Network :: OEA-Tripoli
Password ::OEA@06961
WIFI

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Python
 Python uses an interpreter. Not only can we write complete
programs, we can work with the interpreter in a statement by
statement mode enabling us to experiment quite easily.

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Language terminology
 Syntax: The formal rules for legal statements in the language.
 Semantics: The meaning of the statements - what happens when the
statement is executed.

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Three major control constructs of programming (Execution flow of
instructions)
 Sequential: Simply do steps one after the other in order they are
listed.
 Conditional: Decide which statement to do next based on some
true/false test.
 Iterative: A set of statements is repeated over and over until some
condition is met.

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Sequential Operations “Atomic”
 Input
 Computation
 Output

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The Basic Pattern
 Most of our programs will use the basic pattern of
 Get some user input
 Perform some algorithm on the input
 Provide results as output

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Identifiers
 Identifiers are names of various program
elements in the code that uniquely identify the
elements. They are the names of things like
variables or functions to be performed. They're
specified by the programmer and should have
names that indicate their purpose.
 In Python, identifiers
 Are made of letters, digits and underscores
 Must begin with a letter or an underscore
 Examples: temperature, myPayrate, score2

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Keywords
 Keywords are reserved words that have special meaning in the
Python language. Because they are reserved, they can not be used
as identifiers. Examples of keywords are if, while, class, import.

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Variables in Python
 A variable has
 A name – identifier
 A data type - int, float, str, etc.
 Storage space sufficient for the type.

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Numeric Data Types
 int
This type is for whole numbers, positive or negative. Examples: 23,
-1756
 float
This type is for numbers with possible fraction parts. Examples:
23.0, -14.561

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Integer operators
The operations for integers are:
+ for addition
- for subtraction
* for multiplication
/ for integer division: The result of 14/5 is 2
% for remainder: The result of 14 % 5 is 4
 *, /, % take precedence over +, -
x + y * z will do y*z first
 Use parentheses to dictate order you want.
(x+y) * z will do x+y first.

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Integer Expressions
 Integer expressions are formed using
 Integer Constants
 Integer Variables
 Integer Operators
 Parentheses

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Python Assignment Statements
 In Python, = is called the assignment operator
and an assignment statement has the form
<variable> = <expression>
 Here
 <variable> would be replaced by an actual variable
 <expression> would be replaced by an expression
 Python: age = 19

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Python Assignment Statement
 Syntax: <variable> = <expression>
 Note that variable is on left
 Semantics:
Compute value of expression
Store this as new value of the variable
 Example: Pay = PayRate * Hours
Payrate
10
Hours
40
Pay
400

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Python Session

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Python Session

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What about floats?
 When computing with floats, / will indicate regular division with
fractional results.
 Constants will have a decimal point.
 14.0/5.0 will give 2.8 while 14/5 gives 2.

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Comments
 Often we want to put some documentation in our program. These
are comments for explanation, but not executed by the computer.
 If we have # anywhere on a line, everything following this on the line
is a comment – ignored

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Numerical Input
 To get numerical input from the user, we use an
assignment statement of the form
<variable> = input(<prompt>)
 Here
 <prompt> would be replaced by a prompt for the user inside
quotation marks
 If there is no prompt, the parentheses are still needed
 Semantics
 The prompt will be displayed
 User enters number
 Value entered is stored as the value of the variable

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Print Statement
 For output we use statements of the form
print <expression>
 Semantics
 Value of expression is computed
 This value is displayed
 Several expressions can be printed – separate them by commas

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Example - Fahrenheit to Centigrade
 We want to convert a Fahrenheit temperature to Centigrade.
 The formula is C = (F -32) x 5/9
 We use type float for the temperatures.

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Python Session

Lecture 1-Intro to programming and python.pdf

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