Lesson 1 - Variables, Print, Comments

Welcome to your first lesson. The way this works is easy. Type in the program, run it, see what happens and analyze the results.

Look at each line of code and compare it to the output.

Analyze it by asking answering the following questions:

1. Which line produced the output 'Welcome to my first Python program'?
2. What does the word print do?
3. What happens if you miss the brackets ( )?
4. What happens if you miss the apostrophes ' ' ?
5. What did line 1 do? Remove the hashtag # and try running the program. What can conclude the # does?
6. Why is the # functionality useful? What kind of things would it be good for?
7. What caused the 2nd output (stuff 1 2)? Look at the code. Where did these letters and numbers come from?
8. Why did the computer output the first number 3? What line in the program did this come from?
9. Why did the program output the 2nd number 3?
10. Enter a new line of code that says the following: print z + x
    1. What happens?
    2. What does this mean is the difference between variable z and x?

Program Explanation:

#Lesson 1

• This is called a comment
• Anything after the hashtag is ignored by the program
• This is used to label the program, give notes for human programmers to read, to write your name in the program or hide parts of code you don't want to run

print ('Welcome to my first program')

• The print statement is a command that puts anything in the quotes on the screen
• It must be lower case, and you must have quotes at the start and end of what you want to say

w = ('blah')this is makes a variable called w equal to the word "blah"

• you can use any word for a variable name except for ones that already have meaning (for instance you can't call a variable print)
• you will know the name is legit if it is black. If it turns blue, it has a meaning already
• Here are 7 types of variables you can make in Python (there are more):
  1. bool: Boolean (true/false) types. Supported precisions: 8 (default) bits.
  2. int: Signed integer types. ...
  3. uint: Unsigned integer types. ...
  4. float: Floating point types. ...
  5. complex: Complex number types. ...
  6. string: Raw string types. ...
  7. time: Data/time types. ...

x = ('stuff')

• this makes a variable x equal ot the word "stuff"

y = 1

• this makes a variable y equal to the quantity 1
• since there is a number value after the equal sign, y is now an integer (only numbers)
• you can't add numbers to strings - it won't make sense and you'll get an error. Try it!

z = 2

• this makes an integer z equal to the quantity 2

print (x,y,z)

• this prints the value of x, y and z with a space in between

print (y + z)

• this adds the two variables y and z. Since they are numbers, it gives you the sum

print (1 + 2)

• this adds the value 1 to 2 to get 3. This is just to show you that Python can do math functions

print (w + x)

• this is to show you what happens if you try to add two strings together. It puts them on the screen together without a space.
• you could permanently join them. Try adding t = w + x and then print t.

String Literals

These are things you can do to format what you print. You basically put a \ and a letter matching the effect you want. Try the program below. A summary of string literals is also listed here:

• newline: \n
• backspace: \b
• tab: \t
• backslash: \\
• quote ": \"
• apostrophe: \'

Basic Math Functions:

• add: +
• subtract: -
• multiplication: *
• divide: /
• exponent: ** example x = 2**2
• square root: sqrt() example x = sqrt(4)
• absolute value: abs() example x = abs(-5)
• modulus (returns remainder after division): % example: 5%2 = 1

Assignment #1

Make a program in Python that does the following:

1. Has your name in comments at the top of the program
2. Has 4 variables equal to the letters: a, r, t, s
3. Will output the following words formed by rearranging the 4 letters that the variables are equal to: arts, rats, tars, star
4. Has 4 variables equal to the values: 1, 2, 3, 4
5. Outputs the value of 5 by adding any two of the varaibles
6. Outputs the value of 1 by subtracting any two variables
7. Outputs "1 2 3 4" using only variables

If you have any questions about specifics...ASK!

If you think you can use the print statement without using any variables to complete any part of this assignment, you are WRONG!

Submit your assignment in the standard link below.