PHP Index

In order to become familiar with PHP programming structures and commands, we will build various PHP pages.Sections of this page will explain each PHP command, provide a link to a working sample, and detail the working sample's PHP code. Let's get started:

Comparisons

As previously mentioned, if statements need to evaluate to true or false. Therefore, you need comparison operators to compare values in if statements. Here is a list of comparison operators and several examples.

OperatorOperationExampleResult
== Equal 5==6 False
=== Identical 5===5 True (if same datatype)
!= Not Equal 5!=4 True
<> Not Equal 5<>6 True
!== Not Identical 5!==6 True
< Less Than 3<5 True
> Greater Than 5>7 False
<= Less Than or Equal to 9<=15 False
>= Greater Than or Equal to 15>=5 True

Here's some code:

//set the variable to 7
$dollars=7;

if ($dollars!=5)
{
print("You don't have 5 dollars!");
}
if ($dollars==7)
{
print("You have 7 dollars!");
}

The above code if statements evaluate to true and they print to the browser.

Here's another example:comparisons.php


<html>
<head>
<title>comparisons.php</title>
</head>
<body>


<p>
My Web 2 students have worked hard all year.  Therefore, I've 
been thinking about throwing them a pizza party.  
If they score well on my class quality rating program, 
I will throw them a party before Spring Break.</p> 

<p>They will be rated on:</p>
<ul>
<li>Behavior </li>
<li>Attention</li>
<li>Cooperation</li>
<li>Effort</li>
<li>Enthusiasm</li>
</ul>

<p>Let's use PHP to rate them on each category.  </p>
<?php
//These are variables to hold the ratings
$behavior = "good";
$attention = "bad";
$cooperation = 9.5;
$effort = "bad";
$enthusiasm = 8.5;


//Here are the if statements and comparison conditions to rate them
if ($behavior!="bad") //not equal to
{
print("Bahavior was good.<br>");
}

if ($attention == "good") //equal to
{
print("Attention was good.<br>");
}

if ($cooperation >=9) //greater than or equal to
{
print("Cooperation was good. <br>");
}

if ($effort==="bad") //identical to (including data type)
{
print("Effort was bad. <br>");
}

if ($enthusiasm <7) //less than
{
print("Enthusiasm was bad. <br>");
}
?>

<p>Hmmm...based on the results, it looks like we are destined for ...?</p>
</body>
</html>