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[MUSIC]

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In the last section we started exploring
the two basic pieces of programming,

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storage and retrieval of data,
and the logic that tells what and

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when to do something with that data.

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You were introduced to variables and
we use integers and float variables

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along with arithmetic and assignment
operators, to create a unit converter.

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In this section we'll continue to
expand upon these skills as we explore

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more data types and
logic to create a daily exercise program.

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We'll store each exercise
in a string variable,

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then we'll use conditionals to
control which exercise is displayed.

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Let's start by looking
at the string variable.

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A string is a series of characters
typically specified within quotations.

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You can use either single or
double quotes to create a string but

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they work differently.

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Single quoted strings, for the most
part represent each individual character

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exactly as it is stored in the string.

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Double quoted strings on the other hand
let you place variables inside the string.

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PHP will add the value of the variable or
expand the variable within the string.

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This will make a lot more sense
when you see it in action.

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So let's take a look at an example of
storing and retrieving string variables.

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We're starting a new program, so let's
create a new file and name it strings.php.

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Again, we need to start this file using
the opening and closing PHP tags.

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Then we're ready to add our variables.

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We'll name this variable, string_one.

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Again, we'll use the assignment operator,

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a single equals sign followed by
the value that we want to store.

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In this case, it will be a string
surrounded by single quotes.

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For string one,
let's set it equal to hello world.

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Now that the variable $string_one
contains the value hello world.

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Let's retrieve that value
using echo string one

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and now we can run
the script in the console.

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Great, you've written your
second hello world script.

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As I mentioned before,
the primary difference between single and

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double quoted strings is whether
variable names will be expanded.

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Let's add a variable called name
we'll set this equal to our name.

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I'm gonna use my name, Alena.

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You can use your name.

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Then instead of saying hello world,
let's say hello Alena using the name.

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Save the file and run the script again.

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Notice that the actual variable name
is displayed instead of its value.

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That's because variables are not
expanded within single quotes.

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Let's change these to double quotes and
run the script again.

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Now it works just like I want and
shows hello Alena.

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By using double quotes the PHP
interpreter expands the variable

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showing us the value of the name variable
instead of the variable name itself.

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If you want the value of
a variable within your string

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make sure that you use double quotes.

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There are a few other differences in the way
that PHP interprets characters in a string.

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In the next video, we'll explore
the use of escape sequences.