1. Function introduction mysqli_result::field_seek is a method of the mysqli_result class in PHP, which is used to locate the field pointer to the specified column index position. This function is mainly used when you need to traverse or access field metadata (such as field names, types, etc.), and is often used in conjunction with functions such as mysqli_fetch_field() or mysqli_fetch_field_direct().

In development, we may encounter situations where we need to initiate multiple HTTP requests at the same time. PHP's cURL library provides a very convenient way to initiate multiple HTTP requests in parallel, which is the curl_multi_* function. curl_multi_add_handle and curl_multi_close are two key functions in this type of operation. This article will explain how to use them correctly for multiple cURL request management.

When developing FTP-related applications, we often need to obtain directory structure information on the remote FTP server and further parse and process it. In PHP, the ftp_rawlist function provides the original ability to get a directory list from an FTP server. This article will combine the exploit function to introduce how to efficiently disassemble the return result of ftp_rawlist, so as to quickly obtain the required directory structure data.

When operating a MySQL database using PHP, mysqli_fetch_assoc() is one of the most common results set extraction methods, which returns a row of the result set as an associative array. Mysqli_result::$lengths is a property of the mysqli_result class. After you extract a row from the result set, it returns an array of byte lengths of the fields of the current line.

In PHP, array_filter and array_reduce are both powerful functions for processing arrays, but their uses and how they work are significantly different. Understanding the differences and usage scenarios between these two functions will help to write more concise and efficient code.

clone is a method used to create copies of objects. However, in some cases, there may be some undesirable errors or side effects when copying objects using clone. These errors are usually related to references or resources in objects. To avoid these problems, we can use PHP's serialize function to help us avoid these errors.

In PHP programming, there is often a need to convert numerical values ​​between different digits, especially the conversion between decimal and hexadecimal. PHP provides two very convenient built-in functions, hexdec() and dechex(), for converting hexadecimal numbers to decimal numbers and converting decimal numbers to hexadecimal numbers, respectively.

apcu_entry is a powerful function provided by the APCu extension to implement automatic cache initialization: when the specified cache key does not exist, the callback function will be automatically called to generate cache values ​​and store them. It greatly simplifies cache logic and improves code efficiency.

The role of socket_set_block and the main function of the socket_set_block function is to set a socket to blocking mode. Blocking mode means that when you perform operations such as socket_read or socket_write, if the data is not ready, the program will pause until the data is available or the operation is completed.

What is PHP link function? The basic syntax of the link() function is as follows:

What is mysqli::character_set_name? mysqli::character_set_name is a method in PHP's mysqli extension that returns the character set name used by the current database connection. The prototype of this method is as follows:

In PHP development, json_decode is a common function for parsing JSON data, but in actual use, you often encounter the problem of "illegal JSON characters" causing parsing failure. This article will give you a comprehensive understanding of how to troubleshoot and resolve illegal JSON characters in json_decode, helping you quickly locate problems and successfully complete JSON parsing.

Why use mb_convert_case instead of strtolower or strtoupper? The standard strtolower and strtoupper functions only support ASCII characters. When processing characters such as UTF-8 encoded, they cannot convert non-English characters correctly. For example:

Format string output is a common operation in PHP development, especially when it is necessary to dynamically insert variables and keep the output format consistent. vprintf() is a function used in PHP to format output strings. It is similar to printf(), but unlike it, vprintf() accepts parameters by arrays. This article will give in-depth explanation of the basic usage, applicable scenarios and some practical examples of vprintf().

In PHP, processing image cropping is a very common part of image processing tasks. Since PHP 5.5.0, PHP has built-in imagecrop function to crop part of an image, which is more concise and efficient to use than the previous complicated manual cropping.

1. Understand the array_slice function The array_slice function is used to extract an array of sub-arrays from an array. Its basic syntax is:

When performing numerical calculations and data verification, PHP provides functions for detecting floating point states, such as is_finite() and is_nan(). These two functions are used to determine whether a value is a finite value (that is, it is not infinite or infinite) and whether it is a "non-numeric value" (NaN, Not a Number). In actual development, we often need to use them at the same time to ensure the validity of the values ​​to avoid logical errors or operational exceptions.

In large PHP projects, automatic loading of files and include path configurations are common debugging pain points. Especially when you use include, require, spl_autoload_register or framework's autoloader, if you encounter a class or file loading failure, troubleshooting path problems can be very difficult. Fortunately, PHP provides a built-in function get_include_path() that can help you diagnose and debug these problems.

1. xml_error_string() Introduction xml_error_string() is a function used to obtain the error information corresponding to a single XML error code. Its input parameter is an error code (integral), which returns the text description of the corresponding error code.