Note: If you opened this page from an external URL pay attention that all chapters are linked together. Be sure you also read all prior chapters of this tutorial, otherwise you will miss relevant content explained before.
Now you have all basics of php learned. Sure, there are a lot of more to learn like OOP or references, not to mentioned about extensions like mysqli. However, this is a good point to check the stuff you learned in the chapters before. For this reason there are some questions you should answered before proceeding to the next chapters.
A while loop is used if you dont know how many iterations you will have. The for loop use a special layout to count a variable from one value to another value. So a for loop is used to runs a programm block a given number of iterations.
There are one line comments which starts with // and there
are multi line comments which starts with /* (or /**) and
ends with */.
If you want to call a function use the name of the function. After that you
can provide parameters for the function. These are seperated with commas and
the whole parameter list is written in parentheses. And then the function call
(and all other statements) are finished with a ;.
PHP is only executed and interpreted on the server. Actions like "starting winamp" is not possible. PHP itself just generate a html document.
There are 3 possible ways.
<?php
$var = 10;
$var = $var - 1;
$var -= 1;
$var--;
?>
There are the following datatypes.
boolean
integer
float, double
String
Array
You haven't learned the following datatypes yet.
Object
Resource
Null
Expressions can be concatenate with the dot (.) operator.
<?php
$string1 = "foo";
$string2 = "bar";
$var = "bla"."blu";
$var = "bli".$string1;
$var = $string1.$string2;
?>
A php document starts with <?php and ends with ?>.
A html document starts with the DOCTYPE which defines what kind of html document is used.
First the server sends the headers of the requested file/URL. After that the content is send. If some content is already send (like a space, but also the BOM) the headers cannot be changed as they are gone.
The result is false.
(!(!true XOR true) AND !(!false OR !true)) XOR (false OR (true XOR !false))
(!(false XOR true) AND !( true OR false)) XOR (false OR (true XOR true ))
(!( true ) AND !( true )) XOR (false OR ( false ))
( false AND false ) XOR (false OR false )
( false ) XOR ( false )
false
\n is an escape sequence in php and results in a newline in the output of the html code.
<br /> however is an html tag which creates a new line in the
browsers output.
If the expression in the if part results in false then the
else part gets executed.
break; stops the current loop or switch and continues with the next
php code. continue; cancels the current iteration and begins with the next
one. In a for loop the iteration statement gets also executed.
An index can only be an integer number or a string.
<?php
$array = array(); // create an empty array
for ($i=-10; $i<=10; $i++) {
$array[] = $i;
}
// easier: $array = range(-10, 10);
?>
<?php
// $start and $stop are defined somewhere before
$array = array(); // create an empty array
if ($start%2) { // if the division results in a remaining of 2
$start++; // increase the value by one
}
for ($i=$start; $i<=$stop; $i+=2) {
$array[] = $i;
}
?>
<?php
$number = 3463; // example
$remain = $number % 100;
$number -= $remain;
echo $number;
/* shorter version
$number -= $number % 100;
*/
?>
