LING 398
Elsayed Issa
Jingying Hu
Spring 2026

Lecture Plan (75 minutes):

1. Questions, Installation troubleshooting, and command-line

2. Python Basics

   • Variable assignment
   • Numbers
   • Boolean and the Logic operators
   • The None type

3. Questions

3. Python Programming - Basics I

Objectives:

You will learn:

1. Variable assignment.

2. Basic object types:

   • strings
   • numbers
   • the None type
   • boolean

3. Using some built-in fuctions:

   • print()
   • type()
   • isinstance()
   • int()
   • float()
   • complex()
   • bool()
   • str()

1. Variables and Variable Assignment

• Variables help us to write flexible code.
• In Python, the = symbol represents the assignment operator.

name = "Salem"
print("Name:", name)
print("-----")
age = 20
print("Age:", age)

print("Python is the greatest programming language!")

my_name = "John Johnny"
print(my_name)
my_age = 100
my_age

my_number_list = [1,2,3]
my_number_list

Varibale Names:

• All varibale names are valid except starting with a numerical value or containing .. Both 3varibale and this.varibale are INVALID.
• Variable names cannot contain one of the words reserved by python:
  • for, while, break, pass, continue, try, except
  • in, not, is, import, as, with, if, from, else
  • def, class, return, yield, raises, elif, finally

Practice:

• valid vs. invalid variable name:
  • asd
  • as12
  • for
  • 123
  • None
  • 12_asd
  • num_py

import re
def check(name):
    python_reserved_word = ["for", "while", "break", "pass", "continue", "try", "except", "in", "not", "is", "import", "as", 
                            "with", "if", "from", "else", "def", "class", "return", "yiled", "raises", "elif", "finally", "None"]
    if name in  python_reserved_word:
        return "Invalid"
    if not isinstance(name, str):
        return "Invalid"
    if not re.match(r'^[a-zA-Z_][a-zA-Z0-9_]*$', name):
        return "Invalid"
    return f"`{name}` is a valid varibale name."

print(check("asd"))
print(check("as12"))
print(check("for"))
print(check("123"))
print(check("None"))
print(check("12_asd"))
print(check("course"))

2. Numbers

Types:

• Integers

• Floats

• Complex numbers

2.1 Integers:

• They are whole numbers: ..., -2, -1, 0, 1, 2, ...

# an integer assigned to a varibale called int_number
int_number = 5

# print the value stored in the variable called int_number
print(int_number)

# what is the type of the value stored in the variable called int_number
print(type(int_number))

my_phone_number = 726353536

type(my_phone_number)

my_phone_number2 = "726353536"

type(my_phone_number2)

converted = int(my_phone_number2)
type(converted)

str(123)

int(123)

my_name = "123"
print(type(my_name))

my_int_name = int(my_name)
print(my_int_name)

• The built-in function int is used to identify the type of the integer and convert objects to integer.

# 1) identify the type of the value stored in the variable called int_number 
# (we ask here if the type of value is int or not)
print(isinstance(int_number, int))

# 2) convert "10" to integer
example = "10"
print(type("10"))
print(int(example))

2.2. Floats:

• They are decimal numbers: -0.24, 0.023

# float number assigned to a varibale called float_number
float_number = 0.5983

# print the value stored in the variable called float_number
print(float_number)

# what is the type of the value stored in the variable called float_number
print(type(float_number))

• The built-in function float is used used to identify the type of the float and convert objects to float.

# 1) identify the type of the value stored in the variable called float_number 
# (we ask here if the type of value is float or not)
print(isinstance(int_number, float))

# 2) convert "10" to integer
example = 9
print(type(example))
print(float(example))

n = 1
type(n)

# can we make n a float?
float(n)

Question

• Why do you think 1/3 == .33 returns False?

Please go to the following link: https://docs.python.org/3/tutorial/floatingpoint.html

1/3 == 0.333

2.3. Complex

# integer assigned to a varibale called complex_number
complex_number = complex(5)
print("Complex:", complex_number)
print("Type:", type(complex_number))
print("Type Verfied:", isinstance(complex_number, complex))
print()

print(isinstance(55, int))

print(isinstance("55", str))

Arithmetic Operators

Operator	Meaning
+	addition
-	subtraction
/	division
*	multiplication
**	exponentiation
//	floor division
%	modulus

# addition
3 + 0.4

# exponentiation
2**2

# floor division -> the result rounds to the nearst integer 
21//2

# modulus -> the result is the remainder of a division
a = 7
b = 2

a % b

num_1 = 24
num_2 = 50

my_name = "John"

print(type(my_name))
print(type(num_1))
print(type(num_2))

num_1 + num_2

num_1 / my_name

num_1**num_2

3. Boolean

• There are two boolean-type objects: True and False; they belong to the built-in type bool. We have already seen that the isinstance function either returns True or False, as a given object either is or isn’t an instance of a specific type.

Comparison Operators

Operator	Meaning
==	equal
!=	not equal
>	greater than
<	less than
>=	greater than or equal to
<=	less than or equal to

# Is 5 > 6
5 > 6

5 < 6

# the two boolean-objects: `True` and `False`
type(True)

# `False` is a boolean-type object
isinstance(False, bool)

isinstance(True, bool)

'hat' != 123

#hat = 2

hat != 123

"hat" == "123"

x = "hat"

x != "123"

4. Logic Operators

• Python provides familiar operators for performing basic boolean logic:

Operator	Meaning
and	returns True if both are True
or	returns True if one is True
not	reverse the output

True & False

# demonstrating boolean-logic operators
# and
print(True and False)

# another example
num1 = 3
print(num1 > 1 and num1 < 2)

num_1 = 3
num_1 > 1

num_1 < 2

# or
print(True or False)

# another example
num2 = 3
print(num2 > 1 or num2 < 2)

# not
print(not False)

# another example
num3 = 3
print(not(num3 > 1 or num3 < 2))

# example
print(not(num3 == 4))

5. The `None` Type

• None is used a lot as a placeholder.

type(None)

v = 5
v is None

v is not None

my_name = None