104 lines
1.7 KiB
Markdown
104 lines
1.7 KiB
Markdown
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---
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title: Basic Syntax
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---
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# Basic Syntax
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A PHP script can be placed anywhere in the document.
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A PHP script starts with `<?php` and ends with `?>`
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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
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````<!DOCTYPE html>
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<html>
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<body>
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<h1>My first PHP page</h1>
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<?php echo "Hello World!"; ?>
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</body>
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</html>
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````
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The output of that would be :
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````
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My first PHP page
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Hello World!
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````
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#### Note: PHP statements end with a semicolon (;).
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# Comments in PHP
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PHP supports several ways of commenting:
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````
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<!DOCTYPE html>
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<html>
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<body>
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<?php
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// This is a single-line comment
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# This is also a single-line comment
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/*
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This is a multiple-lines comment block
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that spans over multiple
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lines
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*/
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// You can also use comments to leave out parts of a code line
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$x = 5 /* + 15 */ + 5;
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echo $x;
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?>
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</body>
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</html>
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````
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# PHP Case Sensitivity
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In PHP, all keywords (e.g. if, else, while, echo, etc.), classes, functions, and user-defined functions are NOT case-sensitive.
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In the example below, all three echo statements below are legal (and equal):
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````
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<!DOCTYPE html>
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<html>
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<body>
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<?php
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ECHO "Hello World!<br>";
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echo "Hello World!<br>";
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EcHo "Hello World!<br>";
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?>
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</body>
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</html>
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````
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### However; all variable names are case-sensitive.
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In the example below, only the first statement will display the value of the $color variable (this is because $color, $COLOR, and $coLOR are treated as three different variables):
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````
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<!DOCTYPE html>
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<html>
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<body>
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<?php
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$color = "red";
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echo "My car is " . $color . "<br>";
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echo "My house is " . $COLOR . "<br>";
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echo "My boat is " . $coLOR . "<br>";
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?>
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</body>
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</html>
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````
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