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Foundations of Programming: Fundamentals

Working with operators


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Foundations of Programming: Fundamentals

with Simon Allardice

Video: Working with operators

So we've seen that JavaScript has words like alert and prompt that are causing it to do things to pop up dialog boxes. But also, it's beginning to be obvious that there are symbols like the equals sign that are absolutely as meaningful as words are in a programming language, because this also causes things to happen. It can take the literal value 500, and cause it to be put in the variable called Balance and this equals sign, this assignment operator, is one of many operators in programming languages that will cause things to happen.
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  1. 4m 14s
    1. Welcome
      1m 16s
    2. Making the most of this course
      2m 8s
    3. Using the exercise files
      50s
  2. 22m 11s
    1. What is programming?
      5m 45s
    2. What is a programming language?
      4m 48s
    3. Writing source code
      5m 34s
    4. Compiled and interpreted languages
      6m 4s
  3. 16m 29s
    1. Why JavaScript?
      4m 45s
    2. Creating your first program in JavaScript
      6m 54s
    3. Requesting input
      4m 50s
  4. 31m 38s
    1. Introduction to variables and data types
      5m 16s
    2. Understanding strong, weak, and duck-typed languages
      3m 51s
    3. Working with numbers
      5m 4s
    4. Using characters and strings
      4m 5s
    5. Working with operators
      4m 47s
    6. Properly using white space
      6m 46s
    7. Adding comments to code for human understanding
      1m 49s
  5. 24m 49s
    1. Building with the if statement
      7m 35s
    2. Working with complex conditions
      4m 10s
    3. Setting comparison operators
      6m 59s
    4. Using the switch statement
      6m 5s
  6. 17m 56s
    1. Breaking your code apart
      4m 1s
    2. Creating and calling functions
      2m 57s
    3. Setting parameters and arguments
      6m 7s
    4. Understanding variable scope
      2m 23s
    5. Splitting code into different files
      2m 28s
  7. 13m 32s
    1. Introduction to iteration
      4m 28s
    2. Writing a while statement
      5m 24s
    3. Creating a for loop
      3m 40s
  8. 19m 28s
    1. Cleaning up with string concatenation
      4m 30s
    2. Finding patterns in strings
      8m 3s
    3. Introduction to regular expressions
      6m 55s
  9. 19m 59s
    1. Working with arrays
      5m 47s
    2. Array behavior
      5m 29s
    3. Iterating through collections
      5m 18s
    4. Collections in other languages
      3m 25s
  10. 10m 50s
    1. Programming style
      5m 55s
    2. Writing pseudocode
      4m 55s
  11. 25m 55s
    1. Input/output and persistence
      3m 6s
    2. Reading and writing from the DOM
      8m 11s
    3. Event driven programming
      7m 47s
    4. Introduction to file I/O
      6m 51s
  12. 24m 26s
    1. Introduction to debugging
      5m 57s
    2. Tracing through a section of code
      7m 5s
    3. Understanding error messages
      3m 21s
    4. Using debuggers
      8m 3s
  13. 14m 17s
    1. Introduction to object-oriented languages
      5m 18s
    2. Using classes and objects
      6m 29s
    3. Reviewing object-oriented languages
      2m 30s
  14. 11m 14s
    1. Memory management across languages
      5m 11s
    2. Introduction to algorithms
      4m 2s
    3. Introduction to multithreading
      2m 1s
  15. 29m 20s
    1. Introduction to languages
      1m 42s
    2. C-based languages
      4m 40s
    3. The Java world
      3m 13s
    4. .NET languages: C# and Visual Basic .NET
      6m 17s
    5. Ruby
      3m 4s
    6. Python
      2m 56s
    7. Objective-C
      4m 3s
    8. Libraries and frameworks
      3m 25s
  16. 1m 2s
    1. Where to go from here
      1m 2s

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Foundations of Programming: Fundamentals
4h 47m Beginner Sep 22, 2011

Viewers: in countries Watching now:

This course provides the core knowledge to begin programming in any language. Simon Allardice uses JavaScript to explore the core syntax of a programming language, and shows how to write and execute your first application and understand what's going on under the hood. The course covers creating small programs to explore conditions, loops, variables, and expressions; working with different kinds of data and seeing how they affect memory; writing modular code; and how to debug, all using different approaches to constructing software applications.

Finally, the course compares how code is written in several different languages, the libraries and frameworks that have grown around them, and the reasons to choose each one.

Topics include:
  • Writing source code
  • Understanding compiled and interpreted languages
  • Requesting input
  • Working with numbers, characters, strings, and operators
  • Writing conditional code
  • Making the code modular
  • Writing loops
  • Finding patterns in strings
  • Working with arrays and collections
  • Adopting a programming style
  • Reading and writing to various locations
  • Debugging
  • Managing memory usage
  • Learning about other languages
Subjects:
Developer Web Programming Foundations
Author:
Simon Allardice

Working with operators

So we've seen that JavaScript has words like alert and prompt that are causing it to do things to pop up dialog boxes. But also, it's beginning to be obvious that there are symbols like the equals sign that are absolutely as meaningful as words are in a programming language, because this also causes things to happen. It can take the literal value 500, and cause it to be put in the variable called Balance and this equals sign, this assignment operator, is one of many operators in programming languages that will cause things to happen.

Let's explore a few more of these operators by starting off with a few that you already know how to use. So the most obvious ones are the arithmetic operators. We have operators for addition, subtraction, multiplication, and division which we're using the asterisk for multiplication and the forward slash for division. We're usually using this in combination with the equals sign as well. But let's say we create a couple of variables, variable a = 100, variable b, set it equal to 50, and then we can use the plus sign on the right-hand side of the assignment operator to perform this operation, to add these two together, and save the result in a new variable called result.

in this case this would be 150. Or we can change that plus sign for a minus sign and do subtraction. And I think you know where I am going with the asterisk for multiplication, or the forward slash for division. But what we're doing is evaluating what's on the right-hand side of the equals sign and assigning that value to what's on the left-hand side of the equals sign. Now you can use multiple operators together, but JavaScript like any programming language does have operator precedence.

simply meaning, some of these operator symbols are treated as more important than others. So let's say with this simple statement, if you just read this left to right, you're going to see what's on the right -hand side of the equals sign, and you are going to say 5+5 is 10, *10 is 100. But no, the multiplication is regarded as more important. So the 5*10 is done first which is 50, and then we add 5 to it, and the result would be 55.

If I want to make sure that I can impose an order on this and I have multiple operators, I simply take the important pieces and I surround them with parentheses. So in this one for example, I can make sure that 5+5 will be evaluated by itself as 10, and then multiply it by 10 and we have 100. Now, one thing that's very common is to see the same variable name on both sides of the equals sign. But remember, what we're looking at is to evaluate whatever is on the right-hand side, we take that as an expression.

So the first thing we do here is we look at whatever the current value of score is and then we'll add 10 to it, and then we'll store the result in the variable score. So if its score is 100, it will now be 110. This idea to add a value to an existing variable rather than creating a new variable is so common that there is a shorthand for it which is +=. score += 10 just simply means take whatever the value of the score variable is and add 10 to it. Now, here the + and the = have to be written as one.

There is no space in between them. This is considered one operator, and the same way there is a +=, we also have -=, *=, and a /= for subtract a value or multiply a value or divide a value. Not only that, but it's very common to see something like this. If we want to just add 1 to an existing variable, well we could write it out such as a = a + 1 or we have that shorthand a += 1. But the idea of an increment of just adding 1 to a variable is so common, it actually has its own shorthand which is ++.

a++ simply means add 1 to the variable a. This idea is where the language C++ got its name from. It's the idea of C+1, the next version of C. And the same idea, we can subtract 1 from a variable by writing it long hand a = a - 1, or saying a -= 1 or just a--. The ++ is called the increment operator; -- is called the decrement operator.

So as you can see, these symbols have as much of an importance within a programming language as the words themselves do and we have a few more that we'll explore as the course goes on, but this will be enough to get us started.

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