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Learning Your Second Language

What you will learn

  • Creating Variables in a New Language
  • Conditionals in a New Language
  • Looping in a New Language
  • Collections in a New Language

  • Writing Functions in a New Language

Getting Started

Head over to Repl.it and create a new REPL to practice today's New Language!

Creating Variables

How we did it in Javascript

// We create constant variables with the const keyword
const myConstant = 5
// We create re-assignable variables with the let keyword
let myVariable = "Hello World"

// We Printed Variables to the console using console.log
console.log(myConstant)
console.log(myVariable)

How we do this in Python

# Constants don't exist in python, but convention is to name constants in all CAPS
MY_CONSTANT = 5
# All variable by default are re-assignable, snake case is the norm in python
my_variable = "Hello World"

# We print variables to the console with the print function
print(MY_CONSTANT)
print(my_variable)

Receiving Input

In Javascript we could either use forms, prompt to receive input from the user on the frontend. In node, getting input from the console is a bit more complicated, let's see how we would do that in nodeJS.

// Import Readline Node Library and Create Interface to Read Input
const readline = require('readline').createInterface({
  input: process.stdin,
  output: process.stdout
});
 
// Ask questions, receive input, run callback in response
readline.question('Who are you?', name => {
  console.log(`Hey there ${name}!`);
  readline.close();
});

How would we do that in Python?

# Input function asks the questions and returns input
user_input = input("Who are You?")

# We can interpolate the variable into this print
print(f"Hey there {user_input}")

Conditionals

If statements in Javascript

const num = 5

if (num > 3){
    console.log("num is greater than 3")
} else if (num > 1){
    console.log("num is greater than 1")
} else {
    console.log("num is 1 or less")
}

If statements in Python

num = 5

# The indentation is required in python
if (num > 3):
    print("num is greater than 3")
elif (num > 1):
    print("num is greater than 1")
else:
    print("num is 1 or less")

While Loops

In Javascript

let counter = 0

//This will loop 10 times
while(counter < 10){
    console.log(counter)
    counter += 1
}

In Python

counter = 0

#this will loop 10 times
while (counter < 10):
    print(counter)
    counter += 1

10 Minute Exercise

Write the code to do the following:

  • Loop 10 times starting the counter at 0
  • On each loop if the counter is even print "it's even"
  • If odd, print "meow" if the number is divisble by 3
  • Otherwise print nothing

Collections

In Javascript we have arrays and objects

const myArray = [1,2,3]

console.log(myArray) //logging the entire array
console.log(myArray[0]) // logging an individual item

const myObject = {
    cheese: "gouda",
    bread: "rye"
}

console.log(myObject) //logging the entire object
console.log(myObject.cheese) // logging a property using dot notation
console.log(myObject["bread"]) // logging a property using square bracket notation

In python we have lists and dictionaries

my_list = [1,2,3]
print(my_list) # Printing the whole list
print(my_list[0]) # Printing an individual item

my_dictionary = {"cheese": "gouda", "bread":"rye"}
print(my_dictionary) #Printing the whole dictionary
print(my_dictionary["cheese"]) #accessing one value from the dictionary

10 Minute Exercise

Google Python List Methods/Functions and discover the following and apply them to the following list.

[1,2,3,4,5,6,7,8,9,10]
  • How to find a lists length
  • How to loop over a list
  • How to add and remove items from a list

Functions

in Javascript

const addNums = (x, y) => {
    return x + y
}

console.log(addNums(5,5))

In python

def add_nums (x,y):
    return x + y

print(add_nums(5,5))

10 minute exercise

Write the following functions

  • sub_nums that takes two arguments and returns their difference
  • say_hello that takes a name as an arguments and says hello to that name
  • sayhelloadv that takes a dictionary with a name and age property and prints "hello {name}, how does it feel to be {age} years old"
  • looper takes one array as an argument, it loops over the array and prints each item individually

Resources to Learn More