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File Information

File information is the set of facts a program can check about a file. Small PHP functions answer checks like whether a file exists and how big it is.

A file that exists and one that does not

The setup line writes a real file. The two var_dump lines show true for the written file and false for a missing name.

<?php
file_put_contents("note.txt", "Hello\n");
var_dump(file_exists("note.txt"));
var_dump(file_exists("missing.txt"));

An exact size in bytes

The saved text holds eleven letters and spaces plus one newline. The filesize line prints 12, the exact byte count of that fixed content.

<?php
file_put_contents("size.txt", "Hello files\n");
echo filesize("size.txt"), "\n";

The parts of a path

A path is the text that names where a file sits. pathinfo breaks one path into its parts, and basename picks out the file name part.

<?php
$path = "notes/report.txt";
print_r(pathinfo($path));
echo basename($path), "\n";

Example

<?php
file_put_contents("report.txt", "Report ready\n");
var_dump(file_exists("report.txt"));
echo filesize("report.txt"), "\n";
var_dump(is_file("report.txt"));
var_dump(is_dir("report.txt"));

Key points

  • file_exists reports whether a name exists.
  • filesize gives the size of a file in bytes.
  • A byte is a unit for the size of data, and one plain text character takes one byte.
  • is_file reports whether a name is a regular file.
  • is_dir reports whether a name is a folder.
  • basename gives the last part of a path.

In this example, the program writes one report file and then checks it three ways. file_exists answers true, filesize prints 13 for the thirteen bytes saved, and is_file answers true while is_dir answers false.

Try it Yourself

Edit the code, then press Run.

Running is simulated

Exercise

What does filesize give for a file?