PHP (Hypertext Preprocessor), translated as hypertext preprocessor, is an open source server-side scripting language. Because of its simplicity, ease of learning and powerful functions, PHP has become one of the preferred languages for Internet development. This article will introduce the historical background, basic syntax, common applications and learning methods of PHP.
1. History of PHP
The birth of PHP can be traced back to 1994. At that time, a programmer named Rasmus Lerdorf created a simple script language for recording visits to his resume. ——Personal Home Page Tools (PHP Tools). Two years later, he made this tool open source, and other programmers continued to improve and expand it, eventually forming the now widely used PHP language.
2. Basic syntax of PHP
1. Output
PHP code can output the response HTML or text, using the echo or print function:
<?php echo "Hello, world!"; print("Goodbye, world!"); ?>
2. Variables
Variables in PHP start with the $ symbol. Variable names are required to start with letters or underscores, followed by any number of letters, numbers, or underscores. Variables do not need to declare the type in advance, the system will automatically determine based on the assigned value.
<?php $name = "John"; $x = 5; $is_valid = true; ?>
3. Operators
The operators available in PHP include arithmetic operators, comparison operators, logical operators, etc., which are similar to other languages.
<?php $x = 10; $y = 5; //算术运算符 echo $x + $y; echo $x - $y; echo $x * $y; echo $x / $y; //比较运算符 echo $x > $y; echo $x < $y; echo $x >= $y; echo $x <= $y; echo $x == $y; echo $x != $y; //逻辑运算符 echo $x and $y; echo $x or $y; echo !$x; ?>
4. Conditional statements
The conditional statements available in PHP include if, elseif and else, and the syntax is similar to other languages.
<?php $x = 10; $y = 5; if ($x > $y) { echo "x is greater than y"; } elseif ($x == $y) { echo "x is equal to y"; } else { echo "x is less than y"; } ?>
5. Loop statements
The loop statements available in PHP include for, while, do...while and foreach, and the syntax is similar to other languages.
<?php //for循环 for ($i=0; $i<5; $i++) { echo $i; } //while循环 $x = 0; while ($x < 5) { echo $x; $x++; } //do...while循环 $x = 0; do { echo $x; $x++; } while ($x < 5); //foreach循环 $arr = array("apple", "banana", "cherry"); foreach ($arr as $value) { echo $value; } ?>
3. Common applications and learning methods
1.Web development
The most common application of PHP is Web development, especially based on server architectures such as Apache and Nginx and MySQL Embedded development of databases. Using PHP to develop websites can quickly develop efficient dynamic websites, such as online shopping malls, forums, blogs, etc.
2. Desktop applications
PHP can also be used to develop desktop applications. By using a PHP runtime or framework-based tool like PHP-GTK, you can build native GUI applications using PHP.
3. Learning method
To learn PHP, there are several suggestions you can follow:
In short, learning PHP can not only improve the efficiency of website development, but also develop desktop applications. I hope that the simple introduction and suggestions in this article can help beginners learn PHP better.
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