Aim

To use PHP's built-in library functions for files and directories — creating, copying, renaming, inspecting, listing and deleting — in one self-cleaning demonstration.

Theory

PHP's filesystem library divides into three families:

• Information: file_exists($p) returns true for files and directories; filesize($p) gives the size in bytes; filemtime($p) the last-modified Unix timestamp; basename($p) the final path component; dirname($p) the parent directory; pathinfo($p, PATHINFO_EXTENSION) extracts one component (extension, filename, dirname) from a path. These results are cached per request — clearstatcache() refreshes them after external changes.
• File manipulation: copy($src, $dst) duplicates a file and returns a boolean; rename($old, $new) renames or moves — it is PHP's move function; unlink($p) deletes a file (never a directory) and returns true/false.
• Directories: mkdir($p) creates one (warning and false if it already exists — pair it with is_dir()); rmdir($p) removes one only if it is empty; scandir($p) returns an alphabetically sorted array of entries including the pseudo-entries . and ..; glob("*.txt") returns an array of paths matching a shell-style pattern — a pre-filtered alternative to scandir().

Almost all of these return false on failure, so production code wraps them in checks. The demo also uses uniqid() so every run works inside a brand-new directory and can never collide with a previous run.

Requirements

• XAMPP/WAMP with Apache and PHP 8.x, or the PHP CLI / an online PHP compiler
• Code editor (VS Code); browser or terminal

Procedure

1. Start Apache from the XAMPP Control Panel (or just open a terminal).
2. Save the snippet as p18_file_library.php in C:\xampp\htdocs\wbplab.
3. Open http://localhost/wbplab/p18_file_library.php, or run php p18_file_library.php.
4. Read the output top to bottom — it narrates each function call; because the script deletes everything it made at the end, it can be re-run cleanly any number of times.

Explanation of the Code

• $baseDir is the system temp directory plus wbp_lib_demo_ and a uniqid() suffix; mkdir($baseDir) creates that sandbox for the run.
• file_put_contents($fileA, "Line 1\nLine 2") creates notes.txt with two lines — 13 bytes: six characters per line plus one newline.
• copy($fileA, $fileB) duplicates it as notes_copy.txt; rename($fileB, $renamed) then turns the copy into notes_final.txt — after this the old name no longer exists.
• The echo block reports basename() (notes.txt), the pathinfo() extension (txt), file_exists() rendered as YES/NO through a ternary, and filesize() in bytes.
• The foreach (scandir($baseDir) …) loop lists the directory while explicitly skipping . and .. — the standard idiom.
• Cleanup order matters: both files are removed with unlink() first, and only then can rmdir($baseDir) succeed, because rmdir refuses non-empty directories.

Expected Output

Directory created: with a path ending in wbp_lib_demo_<unique-id> (different every run), then basename(fileA): notes.txt, pathinfo(fileA) extension: txt, file_exists(fileA): YES and filesize(fileA): 13 bytes. The Directory listing using scandir(): block shows exactly two bullets — - notes.txt and - notes_final.txt (the copy exists only under its renamed name). The run ends with Cleanup completed.

🎯 Viva Questions

1. What does scandir() return that a listing usually filters out? The pseudo-entries . (current directory) and .. (parent), which appear in every directory listing.
2. rename() vs copy()? copy() duplicates and leaves the source in place; rename() moves — the old path disappears — and it works across directories, making it PHP's move function.
3. Why can rmdir() fail on an existing directory? It removes only empty directories; the contents must first be unlink()ed (or removed recursively).
4. What happens if unlink() is called on a directory? It fails with a warning — unlink() handles files only; directories need rmdir().
5. What do filesize() and filemtime() return, and what is the stat cache? Byte count and last-modified Unix timestamp; PHP caches these per path, so clearstatcache() is needed for fresh values after outside changes.
6. When would glob() beat scandir()? When only matching files are wanted — glob("*.txt") returns pre-filtered paths with no manual loop over every entry.

CO Mapping

CO1, CO2