how to program, the basics

how_to_program.py

from arepl_dump import dump

#$end

# The first part of programming is simply declaring your variables
# This is very similar to math
x = 1
my_cool_number = 1+1
# my cool number = 1+1 # this doesn't work, no spaces allowed!
z = 2*2
my_list = [1,2,3]

# but you're not just limited to numbers!
aliyah = "awesome person"
dog = {
    "legs": 4,
    "ears": 2
}

# so now we have our data. But what to do with it?
# Programming is about giving commands to a computer
# one such command is print
# you can run commands by typing the name of the command followed by parenthesis
# For example, print()
print()

# That doesn't do anything.. because you didn't tell it what to print
# let's print aliyah from earlier!
print(aliyah)

# we got an awesome person!
# you can print practically anything
print("testing")
print(x)
print(dog)

# What if we want to print a specific number from the my_list?
# You can access lists or dictionaries with []
print(my_list[0])
# this prints the first number of the list
# *HERMOINE FRANTICALLY RAISES HER HAND*: teachER teacher you put 0! 
# Well, in programming lists start at 0.
# Q: Why?
# A: Who cares? Google it.

# What about dictionaries?
# We can get the number of legs for the dog in the same form
# We just pass in a string instead of a number
print(dog["legs"])

# Moving on, you can combine things with +
print(aliyah+" with a great face")

# but you can't combine two different types
# like doritos and ice cream mixed together, computer says barf!
print(aliyah+my_cool_number)

# let's make both of them strings, now things are cool again
print(aliyah+str(my_cool_number))

# Those are the basics, we are a halfway there!
# the beauty of a computer is it allows us to be lazy
# lets say you are punished to write a number a 1000 times
# We could do:
print(1)
print(2)
print(3)
# and I'm tired already
# let's try LOOPS
for number in range(1000):
    print(number)

# that was easy!
# let's break down what we did as a reminder:
# for number in range(1000):
# ^ for and in and the : at the end are special loop syntax. Like lists starting at 0, it's just a fact of life.
#               ^ we ran a command called range and told it to give us a range of 1000 numbers
#    ^ each number gets assigned to the variable `number`
#   print(number)
#   ^ we run the print command
#        ^ and pass in the number!

# we can loop over my_list
for num in my_list:
    print(num)

# We can even loop over the dog!:
for key in dog:
    print(key)

# This won't work, get rid of the # and try to fix it
# (hint: it's missing just one thing!)
#for number in [1,2,3]
#    print(number)

# But what if the teacher changes the punishment to write "foo" if the number is even?
# Do we have to write everything out?
# nope!
for number in range(1000):
    if number%2==0: # %2 divides us by two and gives us the remainder.
        # if it's cleanly divisible then we will get 0 and this path is taken
        print("foo")
    else:
        # otherwise this path is taken
        print(number)

# And if we have to write "buzz" if the number is divisible by 5?
for number in range(1000):
    if number%2==0:
        print("foo")
    elif number%5 == 0: #elif stands for "else if". Sometimes programmers are too lazy to even type out a complete wor
        print("buzz")
    else:
        # otherwise this path is taken
        print(number)

# That's basic programming!
# There's a lot more to learn
# and we lied a tiny bit to simplify things
# but most of programming is just variables, commands, if's, and loops when you get down to it

# OPTIONAL READING:
"""lies:
1. not all languages start at 0. A few langauges like Matlab start at 1.
2. Not all languages use "for foo in bla:" syntax for loops. But the majority of them do have at least the word for
3. In javascript, you CAN combine different types. This is convenient but also leads to a lot of bugs
4. Classes and functions and imports and more are also big parts of programming. But not technically necessary.
"""