3.1-3.2- Variables and Assignments/Data Abstraction
Notes
- A varaible is a abstraction made inside a program that holds a value
- Make sure varaibles are correct
- Boolean are true or false statements
- Integers are numbers
- Lists and dictionary are letters
- A string can represent someones phone number
- A varible is updated by making the varaible equal to something else in a new line
- Sudo code is where syntax doesn't matter
- Python the assignemnt oporator is =
- Quotes means it is a string
- Square brackets are a list
- Javascript in this line of code we are trying to assign the buttons a variable
- Strings are a series of characters
- Lists are sequences of elements where each element in the list is a variable. An order to them
- Using negative numbers you and start the list from the end
- Data abstraction simplies code
- Lists means that the user doesn't need to know the data
- Printing a list of variables can be used with individual variables and the print() code. This is inefficient. You can use a single variable such as score = []. Then print it with print()
Hacks
Hack 1
- An assignment operator is the transition character of a variable. = for python for example
- Collegeboard pseudocode uses an arrow <--- to assign values to variables
- If a variable, x, is initially given a value of 15 and ;ater on changed to 22 it would display 22 because it was changed from 15.
Hack 2
- A list is a series of varaibles that are listed then printed in one
- An element is the characters isside a string
- An easy way to reference elementing in a list or string is to use a print command but also list the number of that varable in the list. If it is the thrid item in the list you can put 2 or negative to if theres four items in the list
- An example of a string is name = "jake"
name = "Jake"
favfood = ["burger", "steak", "burrito"]
print(name, favfood)
food = ["burger", "steak", "burrito"]
print(food[2])
print(food[-1])
num1=input("Input a number. ")
num2=input("Input a number. ")
num3=input("Input a number. ")
add=input("How much would you like to add? ")
# Add code in the space below
numlist = [int(num1), int(num2), int(num3)]
# The following is the code that adds the inputted addend to the other numbers. It is hidden from the user.
for i in numlist:
numlist[i -1] += int(add)
print(numlist)
food = ["pizza", "hot dog", "sushi", "strawberry", "sandwich"]
print(food)
- Lists are better for a program than writing out the code because it makes the code more simple. It allows other programers to understand the code better and make edits easier.
team1 = "Bengals"
team2 = "Saints"
team3 = "Texans"
team4 = "Cowboys"
print(team1, team2, team3, team4)
team = ["Bengals", "Saint", "Texans", "Cowboys"]
print(team)
Vocab
- Variable: a code which maps source symbols to a variable number of bits
- Strings: a sequence of characters terminated with a null characte
- Dictionary: unordered collection that contains key:value pairs separated by commas inside curly brackets
- Lists: a sequence of several variables, grouped together under a single name
- Data Types: a classification that specifies which type of value a variable has and what type of mathematical, relational or logical operations can be applied to it without causing an error.
- Data Abstraction: the reduction of a particular body of data to a simplified representation of the whole
x = 10
y = 11
Students = {
'Names': ['Jake','Brady', 'John'],
'GPA': [4.00, 3.40, 1.8],
'Sports': ['Foootball','Baseball', 'None'],
}
print(Students['GPA'][1])
print(Students['Names'][2])
string1 = "Hello"
string2 = "World"
print(string1, string2)
print(string2, string1)