A php script always starts with <?php and ends with ?> tag.
<?php // This is a comment in php // Additional code goes here ?>
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.
Beside <?php and ?> tag php also supports following tags
- Short open tag <?= ?>
- Asp Tags <% %>, <%= ?>
- Scripting tag: <script language="php">
- Shorthand tag: <? ?>
Note: as of php7 asp and scripting tags are removed.
Using short open tag <?= ?> you do not need to type echo. It prints output directly without using echo.
echo statement can be used with or without parentheses:
Followings are summary of php tags:
<?php echo 'if you want to serve PHP code in XHTML or XML documents, use these tags'; ?> You can use the short echo tag to <?= 'print this string' ?>. It's always enabled in PHP 5.4 and later, and is equivalent to <?php echo 'print this string' ?>. <? echo 'this code is within short tags, but will only work if short_open_tag is enabled'; ?> <script language="php"> echo 'this tag is not supported in php7 anymore'; </script> <% echo 'You may optionally use ASP-style tags however they are removed in php7'; %>
Beside echo function you can also use print function to display contents on browser or console.
<?php print "<h2>Sample Header tag</h2>"; print "example with break line<br>";
In, php you can combine multiple strings using . characters. echo function can take mutliple strings as an argument just like a function however print function take single argument.
<?php echo "This will work\n"; echo "argument-1", "argument-2"; print "This will work\n"; // example of combining two string in one using dot echo "this works" . " and this line is joined\n"; print "this works" . " and this line is joined\n"; // following line wont work // and throws PHP Parse error print "argument-1", "argument-2";
Note: echo function can take multiple arguments however print does not. You can concat multiple lines using dot (.) operator.
To write something on terminal or browser php uses following functions:
Each echo or print statement in php must end with semi colons. 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.
Let's have a look at example:
<?php // first statement echo "Hello world"; // second statement echo "Second statement"; echo 'We omitted the last closing tag';
HTML markup can also be added to php echo statement. To print a bold text on browser you can simply do following code:
<?php echo "<b>This is bold text</b>"; ?>
Everything out side php tag is considered as html content because php is embeded inside html language.
<html> <body> <?php echo "<h1>Sample header tag</h1>"; ?> </body> </html>
PHP supports 'C', 'C++' and Unix shell-style (Perl style) comments. Comments can be of different types:
- Single line comments starts with either // or #
- Multi-line comments starts with /* and ends with */
Comments are not shown on console or browser because they act as developer guidelines.
Let's have a look at some examples of comments:
<?php // This is a single line comment # This is also single line comment /* This is an example of multi-line comment You can add as many lines you want */ //====================================================================== // Author: Sandip Patel //======================================================================
Note: avoid nested comments to prevent fatal errors
What is the correct and the most two common way to start and finish a PHP block of code?
- <?php // code goes here ?>
- <? // code goes here ?>
How can we display the output directly to the browser?
- to display the output directly to the browser, we have to use the special tags <?= and ?>
What are the different ways to write single line comments in php?
- // or #
What are the ways you can declare multi line coments in php?
- /* this is multi-line comment */
Which php tags are deprecated in php7?
- asp Tags <% %>, <%= ?>
- scripting tag: <script language="php">
What is the difference between echo and print functions?
- echo takes multiple arguments however print does not
How do you combine two strings in php?
- You can easily combine or concat two strings using dot (.) operator.
What are the different ways to output a string in php?
- Using print or echo you can output strings in php