|
The following are a few simple examples of PHP, but highlight its
power, and usage.
Printing to the output
The first example simply uses the PHP print statement to display
text to the output screen.
Hello World
PHP code |
| <?php
print("Hello World");
?> |
Executed code |
|
Hello World |
Strings can support escape sequence characters, such as:
| Escape
sequence
|
Description
|
| \n
|
Start a new line |
| \r
|
Carriage return |
| \t
|
Tab space |
| \\
|
Backslash |
| \"
|
Double quote |
| \$
|
Dollar sign |
| \x0yy
|
Hexadecimal character (yy) |
For example:
Escape characters
in PHP code |
| <?php
print("The cost of the subscription is \$10");
print("<br>Please log on with the user name of
<i>\"fred\"</i> with a
password of <i>\"bert\"</i>");
print("<br>Your home directory is <b>C:\\docs\\fred</b>");
?> |
Executed code |
|
The cost of the subscription is $10
Please log on with the user name of "fred" with a password of "bert"
Your home directory is C:\docs\fred |
Comments
PHP is very much based on C and UNIX-type syntax, thus comments
of the form /* and */, and // can be used within the PHP code, and
are completely ignored by the PHP processor. The # character can
also be used in a similar way to the // sequence.
Comments in
PHP code |
| <?php
echo "Testing ...."; // This shows the C++ type
of comment
/* And this is the C type of comment
which is useful for multiple lines */
echo "... 123 ... ";
echo "... 456 ..."; # And a shell style comment
?> |
Executed code |
|
Testing ....... 123 ... ... 456 ... |
Integrating with HTML
As previously seen, PHP supports the integration of HTML tags with
the PHP statements. For example the following code shows an example
of creating a hypertext link in PHP. If an string is to be defined
with the PHP string, then the inverted commas (") and be replaced
with a single quote (').
Integrating
PHP code with HTML |
| <?php
print("<a href='php_test.php'>PHP Test</a>");
print("<br>This is an <b>important</b>
example");
?> |
Executed code |
|
PHP Test
This is an important example |
Variables
Variables have a proceeding '$' sign, and are followed by a space
or an end of string. If you cannot get a space after a variable
then the variable can be enclosed in curly brackets ({ and }). This
is useful when there are no spaces between one variable and the
next.
Examples of
variables in PHP |
| <?php
$value=100;
$username="eee";
$code=123;
print("<BR>Value is $value");
print("<BR>Your user name will be ${username}$code");
?> |
Executed code |
|
Value is 100
Your user name will be eee123 |
Data types
The main data types are Boolean, integer, float, string, array
and object. PHP differs from many other languages in that there
is no integer division, thus 1 divided by 2 gives 0.5. PHP is not
a strongly typed language, thus a numeric variable is automatically
created when a variable is first assigned (using the = character)
to a numerical value, after which it can be used as an integer or
a floating-point value. Numeric values are assigned to be in decimal,
unless they have 0x (for hexadecimal) or 0 (for octal) in front
of them.
Examples of
data types in PHP |
| <?php
$a = 24; # decimal number
$b = -24; # a negative number
$c = 024; # octal number
$d = 0x24; # hexadecimal number
print "<P>$a, $b, $c, $d";
$val1=1;
$val2=2;
$result=1/2;
print "<P>Result of 1/2 is $result";
?> |
Executed code |
|
24, -24, 20, 36 Result of 1/2 is 0.5 |
Strings
Strings can be defined in quotes (between ' and ') or double quotes
(between " and "). If you want a quote in a string use
\", for a new line use \n and a backslash is \\. Also stings
are concatenated together using the '.' operator.
Examples of
data types in PHP |
| <?php
$name1 = "Fred ";
$name2 = "Smith";
print "Hello \"Fred\". How are you?";
print "<br>Your full name is " . $name1 .
" " . $name2;
$name1 .= $name2;
print "<br>Your full name is " . $name1
?> |
Executed code |
|
Hello "Fred". How are you?
Your full name is Fred Smith
Your full name is Fred Smith |
|