PHP's basic syntax includes four key points: 1. PHP tags must start with <?php and end with ?>, and the use of complete tags is recommended; 2. Echo and print are commonly used for output content, among which echo supports multiple parameters and is more efficient; 3. Comments include //, # and //, to improve code readability; 4. Each statement must end with a semicolon, and spaces and line breaks do not affect execution but affect readability. Mastering these basic rules can help write clear and stable PHP code.
PHP is a server-side scripting language that is often used in web development. If you are just starting to get involved in PHP, the most basic and most important thing is to master its syntax structure. A good grammar foundation allows you to write clear, stable and easy-to-maintain code.
1. PHP Tag: Where to Start Writing Code
PHP code must be placed in a specific tag before the server will execute it as PHP. The most common tags are:
<?php // Write your PHP code here?>
Some short tags such as <? or <?= can also be used, but may be disabled in some server environments, so it is recommended to always use the full <?php tag.
Embedding PHP in HTML pages is also common, for example:
<html>
<body>
<h1>Welcome!</h1>
<?php
echo "Hello, world!";
?>
</body>
</html>2. Output content: the difference between echo and print
In PHP, the most commonly used output methods are echo and print . They can all be used to output strings, variables, HTML content, etc.
echohas no return value, and multiple parameters can be output at once (separated by commas):echo 'Hello', ' ', 'World'; // Output Hello World
printcan only output one parameter, and it has a return value (always 1), so it can be used in expressions:if (print("Test")) { // This condition will always be entered}
Generally speaking, echo is recommended because it is slightly more efficient and supports multi-parameter output.
3. How to write comments: Make the code clearer
Comments are parts of the code that will not be executed, but are very useful for understanding code logic. PHP supports three common annotation methods:
- Single line comment:
// - Single line comments:
# - Multi-line comments:
/* ... */
example:
// This is a single line comment# This is also a single line comment/* This is a multi-line comment*/
It is recommended to choose annotation style according to team habits. If it’s a project collaboration, it’s important to maintain a consistent style.
4. Semicolons and Spaces: Don't forget the ending semicolons
Each PHP statement must end with a semicolon ; otherwise it will cause syntax errors. For example:
echo 'Hello'; // Correct echo 'World' // Error: Missing semicolon
In addition, PHP is not sensitive to spaces, and you can wrap or indent any line. However, for readability, it is recommended to maintain a good format:
if ($age > 18) {
echo 'adult';
} else {
echo 'minor';
}Although the following writing method can also be operated, it is not conducive to reading:
if($age>18){echo 'adult';}else{echo 'minor';}Basically that's it. After mastering these basic points, you can start writing simple PHP programs. In the future, you will gradually learn variables, functions, arrays, etc., which will be easier to get started.
The above is the detailed content of PHP Syntax: The Basics. For more information, please follow other related articles on the PHP Chinese website!
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