PHP filemtime filectime fileatime the difference

1, fileatime ()
int fileatime (String filename): the Fileatime () function returns the last time the filename was accessed, where the last access refers to the time when the data block of a file is read, using the UNIX timestamp format , returns False if there is an error.
2, filectime ()
int filectime (String filename): the Filectime () function returns the time that filename was last changed, where the last change is the specified file The inode of filename finally changes the time, where the Inode (index node) is used to store the files and directories of the basic information including time, file name, user and group, using the UNIX timestamp format, error returns false.
(the date is updated when any metadata of the file is changed, including the contents of the permission.) Even if the contents of the file are not changed. )
3, filemtime ()
int filemtime (String filename): the Filemtime () function returns the last modified time of the filename, and the last modification refers to the change in the contents of the file. Uses the UNIX timestamp format, which returns False if there is an error.
(File content modification also includes the content of the file being re-written but the content is not changed but also modified.) )

As for which to see the specific business scenario, I generally use filemtime ()

PHP filemtime filectime fileatime the difference