You cannot view the PHP source code by selecting "View source" in
the browser - you will
only see the output from the PHP file, which is plain HTML. This is because the scripts
are executed on the server before the result is sent back to the browser.
Basic PHP Syntax
A PHP file normally contains HTML tags, just like an HTML file, and some PHP
scripting code.
Below, we have an example of a simple PHP script which sends the text
"Hello World" to the browser:
<html>
<body>
<?php echo "Hello World"; ?>
</body>
</html>
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A PHP scripting block always starts with <?php and ends with ?>.
A PHP scripting block can be placed anywhere in the document.
Each code line in PHP must end with a semicolon. The semicolon is a separator and
is used to
distinguish one set of instructions from another.
There are two basic statements to output text with PHP: echo and
print. In the example above we have used the echo statement to output the
text "Hello World".
Variables in PHP
All variables in PHP start with a $ sign symbol. Variables may contain strings, numbers, or arrays.
Below, the PHP script assigns the string "Hello World" to a variable called $txt:
<html>
<body>
<?php
$txt="Hello World";
echo $txt;
?>
</body>
</html>
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To concatenate two or more variables together, use the dot (.) operator:
<html>
<body>
<?php
$txt1="Hello World";
$txt2="1234";
echo $txt1 . " " . $txt2 ;
?>
</body>
</html>
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The output of the script above will be: "Hello World 1234".
Comments in PHP
In PHP, we use // to make a single-line comment or /* and */ to make a
large comment block.
<html>
<body>
<?php
//This is a comment
/*
This is
a comment
block
*/
?>
</body>
</html>
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