1. Introduction to the strchr() function strchr() is a string function in PHP. Its function is to find the position where a character appears for the first time in a string, and return everything from the beginning of the character to the end of the string. Its alias is strstr(), and both are almost exactly the same in function.

Formatting output is a common requirement, especially when it is necessary to format variables into specific strings and output them. PHP provides a variety of formatted output functions, with printf() and vprintf() being two frequently mentioned functions. They are all used to format output, but there are subtle differences. Understanding their differences helps to select the right function in actual development and improve code flexibility and maintainability.

In PHP development, it is often necessary to format numbers according to the habits of different regions, especially the expressions of currency amounts, decimal points and thousands. PHP provides the setlocale() function to set region information, thereby affecting the display method of formats such as numbers and dates. This article will explain in detail how to use setlocale() to setnumber formats, as well as related format control techniques and practical examples.

In PHP, the substr_count() function is widely used to calculate the number of times a substring appears in a string. It is very efficient when dealing with ASCII characters, but may have unexpected results when faced with multi-byte character encodings such as UTF-8. This article will introduce practical skills of substr_count() when dealing with multibyte character encoding, and help you avoid pitfalls in development through specific examples.

What is curl_multi_remove_handle? curl_multi_remove_handle is a function in the PHP curl_multi extension that removes a single curl handle from a curl_multi handle. Its function is to notify curl_multi not to manage the handle after the multi-handle has processed the request.

When connecting to MySQL databases using PHP, there are many ways to get query results. Mysql_fetch_array and mysql_fetch_row are two commonly used functions. They can all get a row of data from the query results, but the returned data structure and applicable scenarios are different. This article will explain in detail the differences between these two functions and their respective application scenarios.

1. Challenges of Transaction and Insert ID Getting When we perform multiple insert operations or insert data in a transaction, it may be inaccurate to read the autoincrement ID directly through mysqli->insert_id, especially when multi-threaded or multi-user concurrent access. Using the $insert_id property of the preprocessed statement, you can ensure that the insert ID affected by the current statement is obtained.

During PHP development, the highlight_file function is a very convenient tool. It can output specified PHP files in a highlight format, which facilitates developers to quickly view the code structure and syntax. However, when using highlight_file to display file contents directly, if the security check of the file path is not done well, it may cause security risks, such as path traversal attacks or exposing sensitive file contents.

1. Introduction to preg_match_all and preg_replace preg_match_all: used to match all content that conforms to regular expressions in a string and return all matching results. It is suitable for scenarios where all target contents are extracted first and then processed.

In PHP development, especially when handling network communication, the socket_set_block function plays a key role. It is used to control the blocking behavior of sockets and is particularly important for network program debugging in CLI (command line interface) mode. This article will combine best practices to deeply analyze the use and debugging skills of socket_set_block, and sort out common problems to help developers debug PHP network programs more efficiently in CLI mode.

In PHP network programming, the socket_set_block() function is used to set a socket to blocking mode. In blocking mode, socket operations will wait until completion or an error occurs, which is very important in some scenarios. However, calling socket_set_block() sometimes fails, resulting in various error codes. Understanding the meaning of these error codes will help quickly locate problems and effectively debug and solve them.

When using PHP for FTP operations, you often need to know the directory path you are currently in. The ftp_pwd function is used for this purpose, and it can quickly return the working directory path in the current FTP session. This article will introduce in detail how to use the ftp_pwd function, and use sample code to help you quickly understand how to obtain the current FTP directory.

1. What is array_push()? array_push() is a PHP built-in function that adds one or more elements to the end of an array. Its syntax is very simple:

In PHP, operating files is a common requirement, and ensuring that files can be read safely is a key step to avoid program errors and security risks. This article will introduce how to combine the is_readable function and the file_get_contents function to determine whether a file can be read safely.

In PHP development, error logging is an important means to ensure program stability and troubleshoot problems. Although PHP comes with mechanisms such as error_log and set_error_handler, we sometimes want to be able to customize the output format of error messages, especially when it comes to stack trace information. The getTraceAsString() method in the Exception class can help us achieve this.

In daily PHP development, we often need to format dates and times, such as converting timestamps in the database to "year-month-day" formats, or only displaying specific hours and minutes information. The date_format() function in PHP is one of the tools designed specifically for this, which can help us quickly output dates and times in a custom format.

The pathinfo() function is a very practical function used to parse file paths. It can help us quickly obtain various components in the path, such as directory names, file names, extensions, etc. Among these components, PATHINFO_DIRNAME is often overlooked or misunderstood by beginners. Today, let’s take a deeper look at what PATHINFO_DIRNAME is and what its function is.

When executing queries using PDO in PHP, the PDOStatement::getColumnMeta method can help us obtain metadata of a column in the result set, such as field name, data type, length, etc. However, many developers will find that the information returned by this method is often incomplete, especially when using certain database drivers (such as MySQL). This can cause some logic that depends on field metadata processing to errors or behavior abnormalities.

When processing XML data, PHP provides a very practical set of XML parser functions, where xml_parser_get_option is used to obtain a configuration option for the parser. However, many developers will encounter situations that return false when using this function, which is confusing.

The basics of strpos function review The usage of strpos is simple and clear: