- Impact
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Code:
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//Tutorial by deadserious - © [url]http://www.webdesigntalk.net[/url]
//© 2003 [url]http://www.webdesigntalk.net[/url]
//REPUBLICATION OF THE TUTORIAL REQUIRES OUR PERMISSION.
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//To use PHP you'll need to have access to a web server with PHP installed on it. Most Web Hosts offer PHP support. You can also install PHP and run it on your own system which can make it easier to learn and test PHP scripts. CLICK HERE for a tutorial on setting up PHP to run on your own computer.
Okay we'll begin with a simple PHP script for an example.
1.
PHP:
<html>
<head>
<title>PHP TEST</title>
</head>
<body>
<?php
echo 'PHP is easy!';
?>
</body>
</html>If you look at the source code for that page it will look like this:
PHP:
<html>
<head>
<title>PHP TEST</title>
</head>
<body>
PHP is easy!
</body>
</html>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:
<?php
// This is a single line comment.
$var=1;
/* This is a multiline
comment. */
echo $var; // Another single line comment.
?>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.
$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:
<html>
<body>
<?php
$snowboarding = 'fun and sometimes painful';
?>
<font color="green">Snowboarding is really <?php echo "$snowboarding"; ?></font>
</body>
</html>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:
<?php
$snowboarding = 'Snowboarding is really fun and sometimes painful';
?>
<font color="green"><?php echo $snowboarding; ?></font>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 betweeen 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
$name = 'Web';
$lastname = 'Design';
echo "My first name is $name and my last name is $lastname";
?>
The output of this would be:
My first name is Web and my last name is Design
If we do the same with single quotes:
<?php
$name = 'Web';
$lastname = 'Design';
echo 'My first name is $name and my last name is $lastname';
?>
The output would be:
My first name is $name and my last name is $lastname
The same thing is true when assigning variables.
<?php
$name = 'Web';
$lastname = 'Design';
$fullname = "My first name is $name and my lastname is $lastname";
echo $fullname;
?>
The output would be:
My first name is Web and my last name is Design
If we assign the vaules to $fullname with single quotes:
<?php
$name = 'Web';
$lastname = 'Design';
$fullname = 'My first name is $name and my lastname is $lastname';
echo $fullname;
?>
The output would be:
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 Operatros
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 Opertators
&& and (The first and the second is true)
|| or (The first or the second is true)
Some basic math.
<?php
$monthly = 10;
$yearly = 20;
$total=$monthly+$yearly;
echo $total;
?>
The output would be 30.
<?php
echo 2+2;
?>
The out put would be 4.
<?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
$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. :D 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
$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
$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. :D
<?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
$howmuch = 10;
if ($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
$howmuch = 5;
if ($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
$howmuch = 10;
if ($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";
}
?>
Scince $howmuch is not less then or equal to 7 and it doesn't equal 6 the result would be how much is actually 10.
Now you get it right? :D You can add as many elseif statements as you need. You use the else statement for when all else fails.
Using Switch
First an example of an if elseif statement.
<?php
if ($day == 'Monday') {
echo 'Monday';
} elseif ($day == 'Thursday') {
echo 'Thursday';
} else {
echo 'Not today';
}
?>
Now we can get the same results using switch.
<?php
switch ($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.
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