my python notes

“MY PYTHON NOTES”


A computer is an electronic device that stores and processes information

a program is a sequence of instructions that a computer can run.

A library is a collection of code that can be used in other programs

Q: In general, Python programs are _____ than Java programs. 
a.	faster b. longer c. shorter

Q: what syntax required by Java is not required by Python? 
a. semicolons b. parentheses c. quote marks

The error message, EOF stands for End of File.

The print() function displays output to the user. 

Output is the information or result produced by a program.

INPUT:
print("Today", "is", "Monday", sep="? ", end="!!") 
print("I like string beans.") 

OUTPUT:
Today? is? Monday!!I like string beans. 
Note: The end option can be used to continue printing on the same line


INPUT:
print("Please enter your name: ") name = input() print("You entered:", name)

OUTPUT:
Please enter your name: 
sophia
You entered: Sophia

INPUT:
print("Please enter a number: ") number = input() print("Value =", number)

OUTPUT:
Please enter a number: 
six
Value = six

Which is the assignment operator? 
 a. : b. == c. =

Q: writing variable names in snake case,
A: first_name  or  total_price.

RESERVED  BY PYTHON:
False, await, else, import, pass, None, break, except, in, raise, True, class, finally, is, return, and, continue, for, lambda, try, as, def, from, non, local, while ,assert, del, global, not, with, asynch,  elif, if, or, yield.
Q: Which can be used as a variable name?
 a. median b. class  c. import

A string is a sequence of characters enclosed by matching single (') or double (") quotes.

Using len() to get the length of a string

Concatenation is an operation that combines two or more strings sequentially with the concatenation operator (+).

TASK: TRY IT, Name length, Write a program that asks the user to input their first and last name separately. Use the following prompts (example input in bold): 
What is your first name? Alan 
What is your last name? Turing
 The program should then output the length of each name. Based on the example input above,
 the output would be:
 Your first name is 4 letters long 
Your last name is 6 letters long

SYNTAX INPUT:
x=input("what is your first name?: ") y=input("what is your last name?: ") print(f"your first name is {len(x)} letters long") print(f"your last name is {len(y)} letters long")
SYNTAX   OUTPUT:
x=input("what is your first name?: ") y=input("what is your last name?: ") print(f"your first name is {len(x)} letters long") print(f"your last name is {len(y)} letters long")
=== Code Execution Successful ===



TASK: TRY IT, Punctuation, Write a Python computer program that:
 • Assigns the string "Freda" to a variable, name.
• Assigns the string "happy" to a variable, feel.
 • Prints the string "Hi Freda!" with a single print() function using the variable name. 
• Prints the string "I'm glad you feel happy." with a single print() function using the variable feel.
SYNTAX  INPUT:
name="Fareeda"
feel="Happy"
print("Hi " +name)
print("I am glad you feel " +feel)
SYNTAX  OUTPUT:
Hi Fareeda
I am glad you feel Happy

=== Code Execution Successful ===

The format a language uses to represent data is called a data type.
SYNTAX  INPUT:
x=1
print(x,type(x))
SYNTAX  OUTPUT:
1 <class 'int'>

=== Code Execution Successful ===

INPUT:
y=2.0
print(y,type(y))
OUTPUT:
2.0 <class 'float'>

INPUT:
s = "32"
print(s,type(s))

OUTPUT:

32 <class 'str'>

Arithmetic operators are used to perform mathematical operations like addition, subtraction, multiplication, and division. 
Four basic arithmetic operators exist in Python:
1.	Addition (+) 2. Subtraction (-) 3. Multiplication (*) 4. Division (/)

traceback suggests a programmer trace back in the code to find the error if the error is not seen right away.

Each comment begins with a hash character (#). 

Python's first release, known as Version 0.9.0, appeared in 1991, by , Guido van Rossum

A docstring is documentation written for others who will use the program but not necessarily read the source code.

docstrings are generally written as multi-line strings ("""). Common elements of a docstring include a one-line summary, a blank line, and a longer description.

EXAMPLE of docstrings:

"""Vacations Madlib. This program asks the user for two adjectives and two nouns, which are then used to print a funny story about a vacation. """

An expression represents a single value to be computed. Ex: The expression 3*x - 5 evaluates to 7 when x is 4.

Python interpreter translates source code into machine code and runs the resulting program.

A shell, also called a console or terminal, is a program that allows direct interaction with an interpreter

REPL stands for "read-eval print loop,"
1. Read/input some code
 2. Evaluate/run the code
 3. Print any results
 4. Loop back to step 1