basic programming

week 1

program

is a set of instruction given to a computer in a programming language to solve a problem

programming

is the process of writing an algorithm for the computer to program / act of writing a program

programming language

language that the computer understand

algorithm

set of instructions written

process of program execution

input —>process data internally —> output

note to remember

A = 65 B=66 C=67

What is Python?

a general purpose and high interpreted language

4. History

python was inverted in 1980s/1990s by Guido Van Rossum

Programs Are Text Files

we store python program as test files in extension .py

Name Origin

it was named after Monty python’s flying circus

IDE

integrated development environment e.g wing101

functions

• code complier

• debugging

print ()

built in function

print(“hello world”)

argument

"argument

value you pass in a function

comments

• not for the computer

• it always start with #

print(“name”)

When you call a function, the values you pass into it are arguments.

print(name)

When you define a function, the variables listed in the parentheses are parameters.

Logic errors

the program runs but doesn’t not work as expected

Syntax errors

it happens when the program doesn’t follow the programming rules e.i wrong structure and wrong spelling of key words and the program will not start at all

Escape Sequences

scape sequences are special character combinations

\n

newline

\’

prints ‘

\”

prints “

\a

makes a beep sound (bell)

\\

prints back slash \

\b

backspace — deleted the previous character in an output

example print(“Hello\b World”)

output — Hell World

\t

tab , leaves spaces

example print("Name\tAge\tCity")

output — Name Age city

integer

whole number

floating n

fractional number

Integers: Literals

• fixed value written into a code

• example numeric literals 1; 2

common operations

• precedence of operations

• high ()

• middle % * /

• last + -

//

division for integers

that is 3//2 = 1 {floor division}

integer operand

it simply means a whole number

modulus (%)

• remainder

• 5%2 = 1

• 2%4 = 2

Identifiers

names used to identify variables; functions; classes and modules

Rules for Naming Identifiers

• never start with numbers

• start with underscore _ or letters

• it can be followed by numbers

• hyphens - are not allowed

• no spaces

🚫 Invalid characters in identifiers:

• @ (at symbol)

• # (hash)

• $ (dollar sign — except in some languages like JavaScript or PHP)

• !, ?, &, +, -, *, /, etc.

Reserved Words (Keywords)

words that can not be used as identifiers

• Attempting to use reserved words as identifiers will result in a syntax error.

variables

name section memory used to store data

• zenora03 = “Botha”

note

Normally, print adds a newline character (\n) after printing, which moves the cursor to the next line.

sep=’*’

you have to put * between each value and not spaces

end= ‘‘

telling python not to add a newline or space after

prompt

text asking user for input

eval()

a function that converts strings into a number

Increment

x=10

x+=2

x=x+2

x=12

decrement

x=10

x-=2

x=x-2

x=8

Implicit Type Conversions (Type Coercion)

Python promotes int to float in operations if needed.

Explicit Type Conversions (Type Casting)

You can manually convert data types using built-in functions:

note

floats do not become int()

math.ceil

round up

math.floor

rounds down

Comment

a part of code starting with # and is for human reading

Function

performs collective purpose

Identifier

used to name variables and functions

Variable

container for date and named using identifier rules

String literal, numeric literal

fixed words or values used directly

arithmetic operators

-

+

*

/

Syntax

The fundamental rules of a programming language ▪ Similar to the spelling and grammar rules of natural languages