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In PHP, the stream_get_filters function provides a convenient way to list all available stream filters in the current PHP. Stream Filters are functions used to process data streams, such as modifying the contents of streams or preprocessing when reading stream data. This is very useful for handling files, network requests, and even memory streams.
A stream filter is a mechanism that allows data to be modified when it is read or written. PHP provides some built-in stream filters, which also allows users to customize stream filters. Through the stream filter, you can implement operations such as: compressing, encrypting, converting character sets, etc.
The stream filter is used in conjunction with the data stream through PHP's stream operation functions, allowing you to filter or convert during the read and write of the stream.
The stream_get_filters function is very simple. Just call it and it returns an array containing the names of all registered stream filters in the current PHP environment.
array stream_get_filters ( void )
The stream_get_filters function returns an array containing all available stream filter names. If there is no stream filter available, it returns an empty array.
<?php
// Get all currently available stream filters
$filters = stream_get_filters();
// Print filter list
echo "current PHP Flow filters available in：\n";
print_r($filters);
?>
stream_get_filters does not require any parameters, it directly returns an array containing the name of the stream filter.
In the example above, use the print_r function to output all available stream filters.
You can choose the appropriate flow filter to operate on the flow according to your needs.
PHP comes with several commonly used flow filters. Here are some common flow filters:
string.toupper : Converts all characters in the stream to uppercase letters.
string.tolower : Converts all characters in the stream to lowercase letters.
convert.iconv.* : Used for character set conversion, such as convert.iconv.utf-8.iso-8859-1 converts UTF-8 to ISO-8859-1.
zlib.deflate : Deflate the data in the stream.
zlib.inflate : Decompress the compressed data.
To use stream filters in PHP, you usually need to apply the filter in conjunction with stream_filter_append or stream_filter_prepend . Filters can be attached to file streams, network streams, or other types of streams.
<?php
// Open a file stream
$stream = fopen('http://gitbox.net/sample.txt', 'r');
// Use stream filter to convert text to uppercase
stream_filter_append($stream, 'string.toupper');
// Read and output data（It will automatically convert to uppercase）
echo fread($stream, 1024);
// Close the stream
fclose($stream);
?>
In this example, we open a file stream and apply a string.toupper filter to convert all read data to uppercase.
The stream_get_filters function is a very useful tool that helps you list all available stream filters. You can operate on data through these filters to achieve more complex data processing tasks. Understanding and using stream filters can help you process data flows such as files, network requests, etc. more efficiently.
