Because of its two-way real-time communication, WebSocket technology is widely used in online chat, real-time push, game interaction and other scenarios. The performance and stability of network communications become key when building WebSocket services using PHP. The socket_set_block function, as an important tool in PHP socket programming, can help us effectively control the blocking and non-blocking state of the socket, thereby optimizing the response speed and resource utilization of WebSocket services.

When using PHP to process images, the imagecrop() function is a very practical tool that can crop images to specified areas. But if you are dealing with PNG pictures with a transparent background, incorrect processing may cause the transparent background to be lost after cropping and become a black or white background. This article will explain in detail how to keep PNG images transparent when cropping with the imagecrop() function.

The array_slice function is a common function used to extract a fragment from an array. Its basic syntax is as follows:

In PHP, the imagefttext function is a powerful tool for drawing text on images. It supports TrueType fonts and complex text typesetting. Properly specifying text colors is one of the keys to using imagefttext. This article will introduce in detail how to correctly set text colors and help you understand better through examples.

Sliding window algorithm is a common and efficient algorithm idea, which is widely used in problems such as string processing, array search, maximum/minimum subarray and etc. When implementing sliding windows in PHP language, the array_slice function is often used to obtain subarrays of the current window because of its concise and powerful function. This article will explain in detail why array_slice is commonly used in sliding window algorithms, and explain its specific usage in combination with examples.

mb_strcut is a very practical function when using PHP to process multibyte strings. It can intercept the specified byte length of a string without garbled code problems caused by truncating multibyte characters like traditional substr. However, when we operate strings in the database, especially when it comes to multilingual content and encoding conversion, the use of mb_strcut is also prone to some errors. This article will analyze these common errors and their avoidance in detail.

1. Why choose mb_strcut instead of substr or mb_substr? substr will intercept the string according to the byte length, but Chinese characters (such as UTF-8 encoding) usually occupy multiple bytes, which may cause a Chinese character to be truncated from the middle, and then garbled. Although mb_substr can be intercepted by character length, when we paginate the page by "byte number" (if the output is limited to a certain number of bytes), we need to use mb_strcut.

In PHP, the substr_count() function is a very efficient tool, which is used to calculate the number of times a substring appears in a string. However, substr_count() is by default. This is both a convenience and a pitfall for developers: in some scenarios we need to distinguish case-sensitively to process sensitive information, such as distinguishing the frequency of "Word" and "word".

finfo is a very practical extension for obtaining meta information such as MIME type, encoding, etc. of a file. Compared with the traditional mime_content_type() function, finfo provides more accurate and flexible functions. Correct use of finfo can effectively prevent file type disguises and improve file processing security. This article will introduce in detail several correct ways to use finfo and common precautions.

What is the convert_cyr_string function? convert_cyr_string is a function of PHP that converts strings between several Cyrillic letter encodings (such as KOI8-R, Windows-1251, ISO-8859-5, etc.). The function prototype is as follows:

socket programming is one of the basic means to realize network communication. By default, sockets may be non-blocking, meaning that when there is no data, the read operation returns immediately instead of waiting for data to arrive. The blocking Socket will make the program wait while reading data until the data is read, which is suitable for implementing a simple synchronous chat program.

gmdate does not support milliseconds. gmdate receives a timestamp (in seconds) whose formatted string does not have characters specifically representing milliseconds. For example:

Latency is a performance bottleneck that cannot be ignored when building high-performance PHP network applications. Especially in scenarios involving multi-process or cross-process communication, the socket_wsaprotocol_info_import function is often used to share socket handles between different processes. However, frequent use of this function may bring performance burdens, which in turn affects the overall network response speed. This article will start from its working mechanism, explore optimization ideas and evaluate the potential delay improvement.

Why does empty array cause problems? Suppose we write a function that expects to generate a default array of values ​​for subsequent use based on the user-provided key list:

1. Hash_update briefly introduces the usage of hash_update as follows:

1. array_combine Basic usage array_combine receives two arrays as parameters, the first array as key, and the second array as value. If the two arrays have different lengths, Warning is thrown and false is returned.

What should I do if I encounter abbreviation? Abbreviation is a common naming requirement, especially in large projects. To avoid the problem caused by lcfirst directly acting on abbreviation, we can take some tips:

1. Function Overview 1. imagefilltoborder() The function of imagefilltoborder() is to start filling from a certain point in the image until the specified boundary color is encountered. This is similar to the behavior of paint bucket tools.

When operating MySQL databases in PHP, the mysqli extension provides rich functionality to handle database connections, queries, and error management. mysqli::get_warnings is a relatively in-depth but very practical function that helps developers get warning messages generated during database operations. In teaching, rational use of this function can not only improve students' understanding of database operation details, but also help them better troubleshoot potential problems.

1. Introduction to the realpath() function PHP's realpath() function is used to return the absolute path of the specified path and parse the symbolic links, relative paths (such as . and ..) and so on: