Encyclopedia of common PHP built-in objects: Master the understanding of commonly used built-in objects

PHP is a scripting language widely used in web development, with rich built-in objects to implement various functions. This article will introduce commonly used PHP built-in objects and provide specific code examples to help readers better understand and apply these objects.

1. String Object:
   String is one of the most commonly used data types in PHP. Using string objects, you can perform various operations on strings, such as concatenation, replacement, interception, etc. The following is a sample code for a string object:

$str = "Hello World";
$str_length = strlen($str); // 获取字符串长度
$str_upper = strtoupper($str); // 将字符串转为大写
$str_lower = strtolower($str); // 将字符串转为小写

echo "字符串长度：".$str_length."
";
echo "大写字符串：".$str_upper."
";
echo "小写字符串：".$str_lower."
";

2. Array Object:
   Array is a commonly used data structure in PHP, used to store a set of related data . Using array objects, you can perform various operations on arrays, such as searching, sorting, traversing, etc. The following is a sample code for an array object:

$fruits = array("Apple", "Banana", "Orange");

$fruits_count = count($fruits); // 获取数组长度
$fruits_sort = sort($fruits); // 对数组进行排序

echo "水果个数：".$fruits_count."
";
echo "排序后的水果：";
print_r($fruits);

3. File Object:
   File object is used to read and write files. Through file objects, you can open, read, and write files, and you can also perform some other file operations, such as renaming, deleting, etc. The following is a sample code for a file object:

$file_path = "demo.txt";
$file_handle = fopen($file_path, "r"); // 打开文件

$file_content = fread($file_handle, filesize($file_path)); // 读取文件内容

fclose($file_handle); // 关闭文件

echo "文件内容：".$file_content."
";

4. Time object (Date and Time Object):
   The time object is used to process dates and times. PHP provides a wealth of time functions and classes for obtaining the current time, formatting time, performing time calculations and other operations. The following is a sample code for a time object:

$current_time = time(); // 获取当前时间戳

$date_format = date("Y-m-d H:i:s", $current_time); // 格式化时间

echo "当前时间：".$date_format."
";

5. Regular Expression Object:
   Regular expression object is used for string matching and replacement. PHP provides powerful regular expression functions and classes that can perform complex pattern matching operations. The following is a sample code for a regular expression object:

$str = "Hello World";

$pattern = "/Ww+/"; // 匹配以W开头的单词

$matches = array();
preg_match($pattern, $str, $matches); // 进行匹配

echo "匹配结果：";
print_r($matches);

In addition to the objects mentioned above, PHP has many other built-in objects, such as database objects, JSON objects, mail objects, etc., for processing specific functions and requirements. By having an in-depth understanding of these commonly used built-in objects and using corresponding code examples, developers can better utilize the features of the PHP language to implement various complex functions.

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