Intro to: Computers & Programming
Defining Identifiers: Objects with Names
V22.0002-001
Adam Meyers
New York University
Introduction to:
Computers & Programming:
Review for Summer Midterm
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Introduction to Computers & Programming: Review for Summer Midterm, Study notes of Algorithms and Programming
A review for the summer midterm of the course Introduction to Computers & Programming at New York University. It covers topics such as algorithms, programs, programming languages, data types, arithmetic operators, and the assignment operator. The document also includes information on string components, numbers, and identifying objects with names. The document could be useful as study notes or a summary for a student preparing for the summer midterm.
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Intro to: Computers & Programming Defining Identifiers: Objects with Names Adam Meyers New York University
Introduction to:
Computers & Programming:
Review for Summer Midterm
Intro to: Computers & Programming Defining Identifiers: Objects with Names
Summary
- Some Procedural Matters
- Summary of what you need to Know
- For the Test and To Go Further in the Class
- Two Practice in-class writing of programs
- I will give everyone 15-25 minutes to write the same programd independently
Intro to: Computers & Programming Defining Identifiers: Objects with Names Type of Questions that Could Be on the Test
- Section I: Answer questions about Code
- What is printed out?
- What is the value of a variable after code executes?
- Section II: Find and correct errors in code
- Identify errors
- State how to correct the errors
- Note: This type of question will not be on the final.
- Section III: Write functions that solve simple
problems involving: user input, printing,
calculating values, etc.
Intro to: Computers & Programming Defining Identifiers: Objects with Names What you should know
- Topics: algorithm, program, programming language, function, operator, input, output, side effect, variable, scope, data types, simple for loops, etc.
- (^) Know how to:
- Define functions
- Assign values to variables
- Return values from functions
- Use print statements, input statements, operators
- Import modules
- Use data types and coerce one data type to another
- Write a simple function that works and is easy to understand, due to comments and variable/function names
- If/elif/else statements and basic decision trees
- Create graphics with the turtle module
- Basic for loops
Intro to: Computers & Programming Defining Identifiers: Objects with Names
More on Algorithms
- Pseudo Code: a series of ordered statements
- Structured using line numbers, indents, bullets, etc.
- Connected by logical and temporal connectors
- if, else, unless, not, until, when
- Flow Chart: Connected Series of Boxes
- circles/ovals = start/end
- Rectangles = steps in processing
- Diamonds = Decisions
- Arrows = Sequence of Steps
Intro to: Computers & Programming Defining Identifiers: Objects with Names
Functions
- Programming language Functions have 3 optional features: - Input - Output - Side effects
- print versus return
- print is significant for its side effectโprinting to the computer screen
- return
- Exits block (function)
- Provides a value to a function call โ Example:
- If: function1(a) returns 5 and function2(b) returns 10
- Then: function(a) + function(b) = 15
Intro to: Computers & Programming Defining Identifiers: Objects with Names
String Components
- Two identical delimiters: โ, ', '''
- The Characters between delimiters including:
- digits (0-9)
- letters(a,b,c,..z,A,B,C,...,Z, space)
- escape characters: \n, \t, '
- Sample Strings:
- '!@##$^&*())'
- โThis is an apostrophe: ' โ
- 'This is a double quote: โ '
- (^) '''Triple quotes can include ' or โ or between them'''
Intro to: Computers & Programming Defining Identifiers: Objects with Names
More on Strings
- When working with strings they are
represented so it is easy to see all their
components:
- 'The quote ' and the newline \n are useful'
- When printed, a string will be displayed in a
way that interprets these components.
- The quote ' and the newline are useful
- The delimiters are eliminated and escape characters are interpreted.
Intro to: Computers & Programming Defining Identifiers: Objects with Names
Type Conversion Functions (Numbers)
- Float
- Converts Integers and compatible strings to floats
- Int
- Converts floats (by truncation) to integer
- Converts compatible string to integer
- Converted Strings can participate in math operations
- 5 * int('5')
- 20 / float('5.5')
Intro to: Computers & Programming Defining Identifiers: Objects with Names
Converting Non-Strings to Strings
- str(5.55)
- (^) '5.55'
- Makes a string out of any type of object
(using definition of that object)
- Once converted, non-strings can be
combined with strings through concatenation
- 'The number is '+str(5)
- output = 5+
- (^) 'The sum of 5 and 100 is '+ output
Intro to: Computers & Programming Defining Identifiers: Objects with Names
Boolean Operators
- and, or, not
- True and True โ True, True and False โ False, False and True โ False, False and False โ False
- not(True) โ False, not(False) โ True
- False or False โ False, True or False โ True, False or True โ> True, True or True โ True
- <, >, <=, >= โ Expected meanings from math
- ==, != โ 'is equal to', 'is not equal to'
- in โ currently, we only see this in for loops, but it is a Boolean operator that tests for membership, e.g., - 'a' in 'abcdefg' โ True, 5 in range(4) โ False
Intro to: Computers & Programming Defining Identifiers: Objects with Names
Making Code Readable
- Comments
Know How to use comments
Know Why to use comments
- Naming Variables and Functions
- Choosing names that are self explanatory
Intro to: Computers & Programming Defining Identifiers: Objects with Names If/elif/Else Statements
- Syntax (elif and else parts optional) If + boolean-expression + : body elif + boolean-expression + : body else: body
- Example: def classify_integer(integer): if integer==0: return('zero') elif (integer%2) == 0: return('even') else: return('odd')
Intro to: Computers & Programming Defining Identifiers: Objects with Names
Basics of Turtle Graphics
- Loading module, creating a screen and a turtle import turtle my_screen = turtle.Screen() my_turtle = turtle.Turtle()
- Basic Turtle commands
- my_turtle.fd(distance)
- my_turtle.left(degrees)
- my_turtle.pd()
- my_turtle.pu()