Preview
Comparison Operators
6:35Comparison operators allow us to "compare" values and return a true/false result. In this video, we'll be taking a look at the less than and greater than operators and combining operators.
Documentation
Ternary Operator
Another conditional operator is the "?:" (or ternary) operator. The expression (expr1) ? (expr2) : (expr3) evaluates to expr2 if expr1 evaluates to TRUE, and expr3 if expr1 evaluates to FALSE.
Since PHP 5.3, it is possible to leave out the middle part of the ternary operator. Expression expr1 ?: expr3 returns expr1 if expr1 evaluates to TRUE, and expr3 otherwise.
Additional Examples
If we were only checking 60 or greater and we are going to do something in either case, we could also use something like:
if ($score < 60) {
echo 'Please try again';
} else {
echo 'You completed the level!';
}
Related Discussions
Have questions about this video? Start a discussion with the community and Treehouse staff.
Sign upRelated Discussions
Have questions about this video? Start a discussion with the community and Treehouse staff.
Sign up
An operator is something that takes one or
more values and yields another value.
0:00
We looked at several different
operators in the last course.
0:05
Let's review.
0:08
The assignment operator uses the equal
sign to put a value into a variable.
0:09
The arithmetic operators let you add,
subtract, divide, and multiply numbers.
0:14
And the concatenation operators
let you create a new string by
0:20
combining several strings together.
0:24
We also started to look at comparison
operators for equal and identical values.
0:26
In this video we'll learn about some
additional comparison operators.
0:32
Comparison operators do
exactly what they sound like.
0:37
They allow us to compare values and
return a true false result.
0:40
Let's start by taking a look at the less
than and greater than operators.
0:45
Let's create a new file
named conditionals.php.
0:50
Add the opening and closing php tags.
0:58
Then we'll start by creating
a couple variables and
1:03
a simple if statement
like we've done before.
1:06
a=5 and b=5.
1:08
If a is equal to b, echo,
1:13
values are equal.
1:19
Else, echo, values are not equal.
1:27
Let's run the script in our console.
1:37
If your console is not visible,
go to View > Show Console.
1:39
Then type php conditionals.php.
1:44
We see that the values are equal.
1:50
If we change b to equal 10 and
run the script again,
1:53
we see that the values are not equal.
1:58
We can also add a second
conditional to check for less than.
2:02
elseif a is less than b,
2:08
echo a is less than b.
2:14
Because we are using single quotes,
2:21
the variable names will show,
not their values.
2:23
Finally, let's add a third conditional
to check for greater than.
2:27
elseif a is greater than b,
2:33
echo a is greater than b.
2:40
The final conditional and
the else blocks are redundant.
2:49
If the values are not equal and
a is not less than b,
2:53
a must be greater than b, so
we can really use one or the other.
2:57
Since greater than b comes first,
the script conditional will stop there and
3:03
never get to our else statement at all.
3:08
But I'm just gonna leave it there for
right now.
3:10
Let's run our script.
3:13
We see that a is less than b,
because a equals 5 and b equals 10.
3:15
Let's change a to 10 and
run the script again.
3:20
Now we see the values are equal,
because a and b both equal 10.
3:31
Now let's change b to 5 and
run the script once more.
3:36
Now we see that a is greater than b,
because a equals 10 and b equals 5.
3:44
Let's comment out this conditional and
solve for another example.
3:51
Let's say that we want to know
if someone has passed a level.
3:58
And they need to have a final
score of 60 or greater to pass.
4:01
We could add a conditional to check,
if score is greater than 59.
4:06
Then echo, you completed the level!
4:14
Else, echo,
4:25
please try again.
4:29
If we set score equal to 60 or
4:35
greater, then we can run our script.
4:39
And we see, you completed the level.
4:44
If we have a score that's set to 59 or
less, when we run our script,
4:47
we see, Please try again.
4:52
This works fine as long as
we're using whole numbers.
4:56
But what happens if we add
a decimal to 59 and make it 59.5?
4:59
Now when we run the script,
we see, You completed the level!
5:08
Even though our score is less
than the 60 we need to pass.
5:13
59.5 is technically greater than 59.
5:17
So our condition is true, but that's
not exactly what we want to compare.
5:21
Instead, we can combine operators and
use the greater than equal to 60.
5:27
Now, 59.5 will show, Please try again.
5:35
And 60 or greater.
5:40
Will show, You have completed the level!
5:46
In the same way, we can use
the less than or equal to as well.
5:50
Let's say a score of 30 or less will ask
them to practice before they try again.
5:55
So we could add,
6:01
elseif score is less than or
6:04
equal to 30, You should
6:09
practice some more before
6:14
trying this level again.
6:19
Now if we set our score to 30 or less and
6:24
run our script,
we see the message to practice.
6:28