Beginner's Guide to PHP: What is PHP?

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:

• Look for introductory tutorials on the Internet, focusing on learning PHP syntax, variables, and arrays , functions, classes and objects and other basic knowledge.
• Use the knowledge you have learned, write simple code, and debug continuously to become familiar with PHP programming rules and debugging skills.
• Refer to open source PHP projects, such as WordPress and Magento, to understand their code structure and working principles.
• Attend PHP-related conferences and communities to network with other PHP developers.

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.

The above is the detailed content of Beginner's Guide to PHP: What is PHP?. For more information, please follow other related articles on the PHP Chinese website!