When PHP parses a file, it looks for opening and closing tags, which are <?php and ?> which tell PHP to start and stop interpreting the code between them. Parsing in this manner allows PHP to be embedded in all sorts of different documents, as everything outside of a pair of opening and closing tags is ignored by the PHP parser.
A PHP script can be placed anywhere in the document.
A PHP script starts with
<?php and ends with ?>:<?php// PHP code goes here
?>You can use
<? and ?> tag for PHP.To use, you need enable "short_open_tags" in php.ini file.
The default file extension for PHP files is ".php".
If a file is pure PHP code, it is preferable to omit the PHP closing tag at the end of the file. This prevents accidental whitespace or new lines being added after the PHP closing tag, which may cause unwanted effects because PHP will start output buffering when there is no intention from the programmer to send any output at that point in the script.
<?phpecho "Hello PHP Tutorial Example Blog";
// ... more code
echo "Last statement";
// the script ends here with no PHP closing tag
A PHP file normally contains HTML tags, and some PHP scripting code.
Below, we have an example of a simple PHP file, with a PHP script that uses a built-in PHP function "echo" to output the text "Hello World!" on a web page:
Example:
<!DOCTYPE html>
<html>
<body>
<h1>Welcome to PHP Tutorial Example</h1>
<?phpecho "Hello PHP Tutorial Example Blog";?></body>
</html>
Note: PHP statements are terminated by semicolon (;). The closing tag of a block of PHP code also automatically implies a semicolon (so you do not have to have a semicolon terminating the last line of a PHP block).
Comments in PHP
A comment in PHP code is a line that is not read/executed as part of the program. Its only purpose is to be read by someone who is editing the code!
Comments are useful for:
To let others understand what you are doing - Comments let other programmers understand what you were doing in each step (if you work in a group)
To remind yourself what you did - Most programmers have experienced coming back to their own work a year or two later and having to re-figure out what they did. Comments can remind you of what you were thinking when you wrote the code
PHP supports three ways of commenting:
Code:
<!DOCTYPE html>
<html>
<body>
<?php// This is a single line comment # This is also a single line comment /*This is a multiple lines comment block
that spans over more than
one line
$message = "PHP Tutorial Example!";*/?></body>
</html>
PHP Case Sensitivity
In PHP, all user-defined functions, classes, and keywords (e.g. if, else, while, echo, etc.) are case-insensitive.
In the example below, all three echo statements below are legal (and equal):
Code:
<!DOCTYPE html>
<html>
<body>
<?phpECHO "PHP Tutorial Example!<br>";
echo "PHP for beginer!<br>";
EcHo "Lear PHP in one hour!<br>";
?></body>
</html>
However; in PHP, all variables are case-sensitive.
In the example below, only the first statement will display the value of the $color variable (this is because $color, $COLOR, and $coLOR are treated as three different variables):
Code:
<!DOCTYPE html>
<html>
<body>
<?php$color="red";
echo "My car is " . $color . "<br>";
echo "My house is " . $COLOR . "<br>";
echo "My boat is " . $coLOR . "<br>";
?></body>
</html>
No comments:
Post a Comment