PHP commonly used file operation function reference table_PHP tutorial

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Table a

Function	Description	Example
filesize ($file)	This function returns the size of a file in bytes. It is used to calculate how much space a file occupies on disk.	// get file owner and group echo "uid: " . fileowner('myfile.html'); echo "gid: " . filegroup('myfile.html'); ?>
fileatime ($file) filemtime ($file)	These functions return the last time a file was accessed and modified respectively, and are used to find out whether a file has been modified after a specific date.	// get file access/modification times echo "last accessed on: " . date("d-m-y", fileatime('myfile.html')); echo "last modified on: " . date("d-m-y", filemtime('myfile.html')); ?>
fileperms ($file)	This function returns a file permission, use it to check whether the file is readable, writable or executable.	// get permissions in octal format echo "file permissions: " . sprintf('%0', fileperms('myfile.html')); ?>
filetype ($file)	This function returns the "type" of the file - whether it is a connection, directory, attribute or block device, or a regular file. Use it to verify the nature of a file before performing an operation.	// get file type echo "file type: " . filetype('myfile.html'); ?>
stat($file)	This is a "catch-all" function that returns detailed statistics of a file, including its owner and group, size, last modification time, and number of index nodes. If you need comprehensive file statistics in a single function call, use this function instead of those listed previously.	// get file statistics print_r(stat('myfile.html')); ?>
realpath ($file)	This function converts a relative file path to an absolute file path. This function is used when you need to find out the exact location of a file on the disk.	// get absolute path // returns "/tmp/myfile.html" echo "file path: " . realpath("./cook/book/http://www.cnblogs.com/myfile.html"); ?>
basename ($file) dirname ($file)	Given a complete file path, these functions break it into its component parts and return the file name and directory respectively.	// split directory and file names // returns "/usr/local/bin" echo "directory: " . dirname("/usr/local/bin/php"); // returns "php" echo "file: " . basename("/usr/local/bin/php"); ?>
file($file)	This function reads the contents of a file into an array. Each element in the array represents a line of file. This function is used to read the contents of the file into a variable for further processing.	// read file contents $lines = file('myfile.html'); // print line by line for($x=1; $x<=sizeof($lines); $x++) { ?echo "line $x: " . $lines[$x-1] . "n"; } ?>

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