Let's take what we've learned about variables and operators to create a simple

unit converter that can convert pounds to kilograms and miles to kilometers.

You can reverse these calculations,

as well, to determine the number of miles in a kilometer, and pounds in a kilogram.

Check the teacher's notes for

more of the equations used to calculate these conversions.

Do you remember the two basic parts of writing code?

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

when to do something with that data.

So first we'll need to store two pieces of data, the floating point value for

the conversion and the number we want to convert.

Then we'll retrieve that data and perform the calculations.

Then we'll finally display the results.

So let's get started.

Let's create a new file named units.php.

We start by adding the opening and closing php tags and

then we're ready to start writing our program.

Comments are a great way to start.

So let's outline what we'll be doing using comments.

Let's start with pounds to kilograms.

The first thing we need is number in pounds

that we want to convert to kilograms.

Then we need the floating point value for

the pound to kilogram conversion.

Then we'll use the variables

above to calculate pounds multiplied

by the kilogram conversion.

And finally, we display the pounds to kilograms.

Then we'll also convert miles to kilometers.

Again, we start with the number in miles we want to

convert to kilometers.

Then we need the floating point value, For

the mile to kilometer conversion.

Then we need to use the variables

above to calculate miles multiplied

by the kilometer conversion.

And finally, we'll display the miles to kilometers.

Now we're ready to start creating our variables.

We'll start with our variable name $pounds.

You can assign this whatever value you want.

I'm going to use 140.

We'll then create our next variable named $lbs_to_kg.

And we'll set this equal to 0.453592,

which is how many kilograms go into one pound.

We can now perform the calculation and

assign it to a third variable named $kilograms.

$pounds * $lb_to_kg

will give us our kilograms.

And finally, we can display the results to the screen.

Let's start this with some text.

Our weight, Echo our $pounds.

Then we'll echo some more text.

Our lb = $kilograms.

Echo "kg".

Now, let's run the script and see what we get.

Great, just what we want.

The weight, 140 pounds,

equals 63.50288 kilograms.

Let's add a space right here.

And now we're ready to set up our miles to kilometers.

We start with a variable named $miles and we'll set this equal to 2.5.

We then create a variable named $mile_to_km and

we'll give it a value of 1.60934,

which is how many kilometers are in one mile.

Now we perform the calculation and assign it to the third variable, $kilometers.

$miles * $mile_to_km will give us our kilometers.

And finally, we display the results to the screen.

Echo our text will say "Distance:".

Echo our $miles and

then "miles =",

our $kilometer.

And then we'll echo out km.

Now let's run the script and see what we get.

Great, we can see distance added to the end.

2.5 miles equals 4.02335 kilometers.

We'll learn more about formatting in the next section.

Fantastic job putting your new knowledge of variables and operators to work.

Can you reverse the operations and convert kilograms to pounds, and

kilometers to miles?

Or choose a different conversion to implement, such as Fahrenheit to Celsius?

As you practice,

you'll become much more comfortable with using your PHP skills to solve problems.

In the next section, we'll explore different data types for

variables, use conditional operators, and

start implementing conditional logic to create a daily exercise program.

So hurry back to continue flexing our muscles.