Skip to content

python-guide-english.md

Latest commit

 

History

History
267 lines (184 loc) · 6.34 KB

python-guide-english.md

File metadata and controls

267 lines (184 loc) · 6.34 KB

Python Learning Aid (MACHINE TRANSLATED)

  • One line is executed after the other.
  • Comments are written with a # at the beginning of the line. (They are ignored by Python)

Data Types

There are different data types in Python:

  • Integer (Whole number)

    5

  • String (Text)

    "Hello World!"
"123" # This is also a string because it is in "", even if it only contains numbers
# You cannot do math with strings.

  • Float (Decimal number)

    3.14

  • Boolean (True or False)

    True
False

Converting Variables

Examples:

int(x)   # Convert to integer (whole number)
str(x)   # Convert to string (text)
float(x) # Convert to float (decimal number)

age = "17" # String (text)
age_number = int(age) # Convert to integer (whole number)

Assigning Variables

You can create variables and assign values to them. You can name them as you like, but it's good if the name relates to their content.

a = 5 # Integer (whole number)
b = 10
name = "Alex" # String (text), must have "" or ''

Calculating with Variables

Operators:

  • + Addition
  • - Subtraction
  • * Multiplication
  • / Division
  • % Modulo (remainder of division)
c = a + b # c will be 15 because 5 + 10 = 15
c = a * b # c will be 50 because 5 * 10 = 50
a = a + 1 # a is increased by 1, so a = 6

Modulo operator returns the remainder of a division:

10 % 2 # Returns 0. When you divide 10 by 2, the remainder is 0.
23 % 2 # Returns 1. 23 / 2 is 11 with remainder 1.

Console Output/Input

print("Hello World!") # Prints "Hello World!" to the console

User input

print("What is your name?: ")
name = input() # The user must enter something in the console, which is then stored in the variable 'name'
# Shortcut:
name = input("What is your name?: ")

if-else (Conditions)

It first checks the condition of if. If the condition is true, the code block below is executed. If not, the next elif condition is checked, and if none of the conditions are true, the else block is executed.

You must always press Tab to indent.

if a < b: # If a is less than b
    print("a is less than b")
elif a == b: # If a is equal to b
    print("a is equal to b")
else: # If none of the previous conditions apply
    print("a is greater than b")

Loops

There are 2 types of loops: for and while

for loop

Used for a specific number of iterations:

fruits = ["Apple", "Banana", "Cherry"]
for fruit in fruits: # 'fruit' is the temporary variable used for each element in the array 'fruits'
    print(fruit) # prints each value of the array (Apple, Banana, Cherry)

while loop

Used as long as a condition is true:

a = 0
b = 5
while a < b: # As long as a is less than b
    print("a is less than b")
    a = a + 1 # Increases a by 1 so the loop eventually ends, otherwise it would be an infinite loop

To make an infinite loop, you can write while True:.

Getting Input from the User

print("Please enter your name:")
name = input()
# DOES THE SAME AS:
name = input("Please enter your name:")
# Important: input() always returns a string! If you want to get a number (integer), do e.g.:
number = int(input("Enter a number: "))

String Interpolation (Insert variables into strings/text)

There are 2 variants:

print("Hello " + name + ", welcome!") # '+' joins strings
print(f"Hello {name}, welcome!") # You must add 'f' at the beginning to insert variables with {}

If the variable is a number, you must first convert it to a string:

age = 17
print("I am " + str(age) + " years old.")
print(f"I am {age} years old.") # You must add 'f' at the beginning to insert variables with {}

Arrays

Instead of just one variable with one value, you can define an array with a list of values:

fruits = ["Apple", "Banana", "Cherry"]
print(fruits[0]) # prints the first value of the array (Counting starts at 0) (Apple)
print(fruits[1]) # prints the second value of the array (Banana)

new_fruit = "Orange"
fruits.append(new_fruit) # Adds 'Orange' to the array 'fruits'
# ["Apple", "Banana", "Cherry", "Orange"]

Convert a string to an array (list):

text = "Apple"
text_array = list(text)
# text_array -> ['A', 'p', 'p', 'l', 'e']

To do something, for example, 10 times:

for i in range(10):
    print(i) # Prints the numbers from 0 to 9 (0, 1, 2, 3, 4, 5, 6, 7, 8, 9)
# 'range(10)' would create an array with the values 0 to 9 ([0, 1, 2, 3, 4, 5, 6, 7, 8, 9]).

Count entries in an array:

fruits = ["Apple", "Banana", "Cherry"]
number_of_fruits = len(fruits) # Returns the number of entries in the array 'fruits' (3 in this case)

Modules

You can import modules to use additional functions.

Examples:

import random
random_number = random.randint(1, 10) # Returns a random number between 1 and 10

fruits = ["Apple", "Banana", "Cherry"]
random_fruit = random.choice(fruits) # Returns a random fruit from the array 'fruits'
print(random_fruit) # "Cherry" or "Banana" or "Apple"

Functions

You can create your own functions to encapsulate repeating logic and make the code clearer.

def greeting(name): # Function with one parameter 'name'
    print(f"Hello {name}, welcome!") # Prints a greeting

name = input("What is your name?: ")
greeting(name) # Calls the function 'greeting' with the parameter 'name'

def sum_numbers(number_one, number_two): # Function with 2 parameters 'number_one' and 'number_two'
    return number_one + number_two # Returns the sum of number_one and number_two

a = 5
b = 10
result = sum_numbers(a, b) # a fills the parameter 'number_one' and b fills the parameter 'number_two'
print(f"The sum of {a} and {b} is {result}.") # Prints the sum of a and b

My example solutions to some of the more difficult tasks

https://github.com/Alex7k/simple-python-scripts/tree/main/python