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Using characters and strings

From: Foundations of Programming: Fundamentals

Video: Using characters and strings

When we want to deal with text in our programs, characters, words, sentences, email addresses, we use the term strings to describe those kind of values. Now we've seen these already. Anytime you see words contained in sets of quotes, we're dealing with strings. The first line of code that we wrote was this alert message that used the string "Hello, world". This value contained in the double- quotes is referred to as a string literal, just like the number 5 or the number 1,000,000 would be a numeric literal.

Using characters and strings

When we want to deal with text in our programs, characters, words, sentences, email addresses, we use the term strings to describe those kind of values. Now we've seen these already. Anytime you see words contained in sets of quotes, we're dealing with strings. The first line of code that we wrote was this alert message that used the string "Hello, world". This value contained in the double- quotes is referred to as a string literal, just like the number 5 or the number 1,000,000 would be a numeric literal.

We can of course use this format to create variables. I could create a new variable called message and set it equal to the words "Hello, world". I could then use that variable and pop out another alert box. So we are using the string literal to create the variable called message and then writing that variable out. Now, notice that I'm not using double- quotes around message in this second alert statement because I don't want to write out the word message. I want to write out the value of the variable called message.

Now, when we are creating strings, you can use double-quotes to surround the text or the sentence. You can also use single quotes. What you can't do is mix the two. You can't for example open with a single quote and close with a double quote. Most other programming languages restrict you to just double quotes. So I tend to use that in JavaScript to just to make it easier to go from language to language. One of the reasons you might change between the two formats is if you need to have quotes inside quotes.

Let me show you what I mean. Let's say for example we want the phrase Don't mix your quotes contained inside a string. Well, if we used single-quotes to mark out the start and the end of the string we're going to have a problem, because there's also a single quote in the middle of it, and that's how we're telling JavaScript where the string begins and where it ends. So what I could do here is use double-quotes with a single-quote contained inside them. That would be perfectly fine. However, that gets a little tougher when we have a more complex sentence.

Let's say for example we want a phrase that contains both double quotes and single quotes. Well, there is no simple way to mark out the beginning and the end of this without doing something else here. If this is what we need, what we can do is what's called escaping the quotes. This would be the way that I'd have to write it. The entire string begins and ends with double quotes and that means if I want double quotes inside that string, I mark them by putting a backslash before the double quotes being used inside the body of the string itself.

Now, one of the great benefits of dealing with strings in most programming languages is they are smart. These variables go beyond just having a holding place for some characters. We can ask things of them. We'll get into this a lot later, but just to give you a basic example, let's say I create a new variable called phrase and set it to the words "This is a simple phrase." Well, one of the things I can do is I can use the name of that variable to access or get to information about it, such as how long is it.

I can also ask questions of it, like does another word exist inside it? I can convert it to upper or lowercase. As the most straightforward example here, I am going to write the line alert and then instead of just the name phrase, I am going to say phrase.length. This is allowing me to get to what is called the length property of this variable, and what's going to happen is this will pop up an alert box that will say in this case 24. We can actually ask questions of our string variables.

As we get deeper into creating and working with any language, you will find this is very common, but variables by themselves aren't dumb. They can actually give us more information about the contents and about what they're holding. Now we'll get deeper into strings a little later on, but that's enough to get us started.

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This video is part of

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Foundations of Programming: Fundamentals

61 video lessons · 92464 viewers

Simon Allardice
Author

 
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  1. 4m 15s
    1. Welcome
      1m 17s
    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 48s
    1. Building with the if statement
      7m 35s
    2. Working with complex conditions
      4m 9s
    3. Setting comparison operators
      6m 59s
    4. Using the switch statement
      6m 5s
  6. 17m 54s
    1. Breaking your code apart
      4m 1s
    2. Creating and calling functions
      2m 56s
    3. Setting parameters and arguments
      6m 7s
    4. Understanding variable scope
      2m 23s
    5. Splitting code into different files
      2m 27s
  7. 13m 31s
    1. Introduction to iteration
      4m 28s
    2. Writing a while statement
      5m 24s
    3. Creating a for loop
      3m 39s
  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 58s
    1. Working with arrays
      5m 46s
    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 25s
    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 2s
  13. 14m 16s
    1. Introduction to object-oriented languages
      5m 18s
    2. Using classes and objects
      6m 28s
    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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