Okay we'll begin with a simple PHP script for an example.
1.
PHP Code:
PHP Code:
<html>
<head>
<title>PHP TEST</title>
</head>
<body>
<?php
echo 'PHP is easy!';
?>
</body>
</html>
Copy that code into your favorite text editor, note pad will work just fine. Save it as test.php. Make sure it ends with a .php extension. Upload it to where you store your web accessible files and call it up in your browser. If you see "PHP is easy!" then you know PHP is installed and working on your server. Notice the <?php and the ?> these are the start and end tags, they say hey parse up some PHP and hey stop parsing now. You can just use <? for the start tag if the short tag is enabled on your server. Also notice the semicolon at the end of the echo statement. This tells the parser where one line of code ends and the next one begins. You could do this just as easily with regular html, but we needed an example to show you how it works right?
If you look at the source code for that page it will look like this:
HTML Code:
<html> <head> <title>PHP TEST</title> </head> <body>
PHP is easy!
</body> </html>
You can't view the sever side scripts source code from your browser. It will be removed by the time it gets to your browser for viewing. The only code you'll be able to see is the regular html that was included in the script and/or generated by it.
PHP Comments
Comments are used for helping the user and/or the developer remember and understand what the program does and/or provide instructions. You can use single or multiline comments. Comments will be stripped out of the program and ignored by the interpreter.
Example:
PHP Code:
PHP Code:
<?php
// This is a single line comment.
$var=1;
/* This is a multiline
comment. */
echo $var; // Another single line comment.
?>
PHP Variables.
You can define a variable to store for later use. Variables start with the $ sign and are assigned with the = operator . To use a variable you need to assign a value to it.
PHP Code:
$snowboarding = 'fun';
The name of the variable is on the left of the = sign and the value is on the right. In this case $snowboarding has the value of fun. Variables can contain numbers, letters, and underscores, but may not begin with a number.
Some examples of using variables.
PHP Code:
PHP Code:
<html>
<body>
<?php
$snowboarding = 'fun and sometimes painful';
?>
<font color="green">Snowboarding is really <?php echo "$snowboarding"; ?></font>
</body>
</html>
The output of this code would be:
Quote:
|
Snowboarding is really fun and sometimes painful
|
echo prints the output to the browser. You can also use print, but there is slight difference between the two. Also notice how you can jump in and out of PHP mode when ever you wish, and how the variable contains it's value through out the script, but only when you are in PHP mode. Okay so now you get the idea of mixing PHP in with HTML.
More examples of using variables.
PHP Code:
PHP Code:
<?php
$snowboarding = 'Snowboarding is really fun and sometimes painful';
?>
<font color="green"><?php echo $snowboarding; ?></font>
The out put of this code would be the same as above:
Quote:
|
Snowboarding is really fun and sometimes painful
|
If you are just echoing a variable you don't need to surround it with quotes.
The difference between single and double quotes
If you want to print out the value of a variable within a string you need to surround the string with double quotes otherwise the actual variable name will be printed out.
PHP Code:
<?php
$name = 'Web';
$lastname = 'Design';
echo "My first name is $name and my last name is $lastname";
?>
The output of this would be:
Quote:
|
My first name is Web and my last name is Design
|
If we do the same with single quotes:
PHP Code:
<?php
$name = 'Web';
$lastname = 'Design';
echo 'My first name is $name and my last name is $lastname';
?>
The output would be:
Quote:
|
My first name is $name and my last name is $lastname
|
The same thing is true when assigning variables.
PHP Code:
<?php
$name = 'Web';
$lastname = 'Design';
$fullname = "My first name is $name and my lastname is $lastname";
echo $fullname;
?>
The output would be:
Quote:
|
My first name is Web and my last name is Design
|
If we assign the vaules to $fullname with single quotes:
PHP Code:
<?php
$name = 'Web';
$lastname = 'Design';
$fullname = 'My first name is $name and my lastname is $lastname';
echo $fullname;
?>
The output would be:
Quote:
|
My first name is $name and my last name is $lastname
|
In summary variables aren't replaced with their value unless they are surrounded by double quotes with a few exceptions.
Using Basic Operators
Comparison operators compare two values.
== is equal to
!= is not equal to
< is less than
> is greater than
<= is less than or equal to
>= is greater than or equal to
Arithmetic Operators
Just like on a calculator.
+ Addition
- Subtraction
* Multiplication
/ Division
Logical Operators
&& and (The first and the second is true)
|| or (The first or the second is true)
Some basic math.
PHP Code:
<?php
$monthly = 10;
$yearly = 20;
$total=$monthly+$yearly;
echo $total;
?>
The output would be
30.
PHP Code:
<?php
echo 2+2;
?>
The out put would be
4.
PHP Code:
<?php
$monthly = 10;
$yearly = 20;
$monthly+=10; //Same as $monthly=$monthly+10;
$yearly+=10;
$total=$monthly+$yearly;
echo $total;
?>
The out put would be
50.
PHP Code:
<?php
$monthly =10;
$monthly++; //Adds one to monthly. The same as $monthly=$monthly+1;
echo $monthly;
?>
The output would be
11.
The same would work with - and --
Note: ++ and -- are Incrementing/Decrementing Operators and += is an Assignment Operator just like the = sign.
Easy enough right?
Yes it's that easy. For the basics anyways.
String Operators.
. concatenate (put two strings together) Returns the concatenation of its right and left arguments.
.= (concatenate and assign) Appends the argument on the right side to the argument on the left side.
PHP Code:
<?php
$name = "Web";
$fullname = $name . "Design";
echo $fullname;
?>
Now $fullname contains WebDesign. The . is used to put two strings together.
The output of this would be
WebDesign
If we wanted to put a space in there we could do it like this:
PHP Code:
<?php
$name ="Web";
$fullname = $name ." " ."Design";
echo $fullname;
?>
Now the output would be Web Design. To make it even easier we could write the variable like $name = "Web "; so that the space is already there.
PHP Code:
<?php
$name = "Web ";
$name .= "Design";
echo $name;
?>
Now $name would contain Web Design. So the output would be Web Design.
PHP Control Structures
Using if, elseif, and else, to check for certain conditions.
Examples:
PHP Code:
<?php
$howmuch = 10;
if ($howmuch == 10) {
print 'how much is 10';
}
?>
This checks to see if the variable $howmuch is equal to 10. If it is it goes on and executes the code between the curly braces. In this case the result would be how much is 10.
Sometimes you may want to make the script do something if the if condition is not true.
PHP Code:
<?php
$howmuch = 5;
if ($howmuch >= 10) {
print 'how much is 10 or greater';
} else {
print 'how much is not enough';
}
?>
This checks to see if the variable $howmuch is greater than or equal to 10 and if it is then it prints how much is 10 or greater. If $howmuch is not greater than or equal to 10 then it bypasses the code in in the first set of curly braces and executes the code within the else statements curly braces. In this case the result would be how much is not enough.
You can also check for mutltiple conditions with elseif.
PHP Code:
<?php
$howmuch = 10;
if ($howmuch <= 7) {
print 'how much is less than or equal to 7';
} elseif ($howmuch == 6) {
print 'how much is 6';
} else {
print "how much is actually $howmuch";
}
?>
Since $howmuch is not less then or equal to 7 and it doesn't equal 6 the result would be how much is actually 10.
Now you get it right? You can add as many elseif statements as you need. You use the else statement for when all else fails.
Using Switch
First an example of an if elseif statement.
PHP Code:
<?php
if ($day == 'Monday') {
echo 'Monday';
} elseif ($day == 'Thursday') {
echo 'Thursday';
} else {
echo 'Not today';
}
?>
Now we can get the same results using switch.
PHP Code:
<?php
switch ($day)
{
case "Monday":
echo 'Monday';
break;
case "Thursday":
echo 'Thursday';
break;
default:
echo 'Not today';
break;
}
?>
You can use switch as an alternative for if elseif statements. It's good to use switch when you're checking for alot of conditions rather than having huge elseif statements.
