Aim

To read a previously created file and display its content using PHP's file-reading functions.

Theory

PHP offers several reading strategies with different memory profiles:

• file_get_contents($path) slurps the whole file into one string — the simplest option and the fastest for small files, but it holds the entire file in memory at once.
• The handle API reads under manual control: fopen($path, "r") opens read-only (failing if the file is missing), fread($handle, $length) returns up to $length bytes from the current pointer position, and fclose($handle) releases the handle. Passing filesize($path) as the length is the classic "read it all" idiom — same result as file_get_contents(), but with an explicit handle that could also seek (fseek()) or read in chunks.
• For files too large to hold in memory, read incrementally: while (!feof($handle)) { $line = fgets($handle); … } processes one line per iteration in constant memory — the right shape for logs. Related helpers: file() returns the file as an array of lines; readfile() streams a file straight to the output buffer.

One web-specific caution: file text is data, not markup. Before echoing file content into an HTML page it should pass through htmlspecialchars(), or any <script> stored in the file would execute in the visitor's browser.

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 p19_read_file.php in C:\xampp\htdocs\wbplab.
3. Open http://localhost/wbplab/p19_read_file.php, or run php p19_read_file.php — the script writes its own sample file first, so no manual preparation is needed.
4. Compare the two printed blocks: both show the same three lines, retrieved by two different mechanisms.

Explanation of the Code

• The opening file_put_contents() seeds wbp_read_demo.txt in the system temp directory with three \n-separated lines — standing in for "the previously created file" (Practical 17) so the demo is self-contained.
• Method 1: file_get_contents($filePath) returns the complete text in one call, echoed under the Using file_get_contents(): heading.
• Method 2: fopen($filePath, "r") obtains a read-only handle; fread($handle, filesize($filePath)) asks for exactly as many bytes as the file holds, so a single call drains it; fclose($handle) then releases the handle.
• Both methods print identical text — the point of the practical is the mechanism: one-shot convenience versus explicit handle control.

Expected Output

Two labelled blocks with the same content: Using file_get_contents(): followed by First line, Second line, Third line, then a blank line, then Using fopen()/fread(): followed by the same three lines again. In a browser the lines appear run together (newlines are not <br> tags) unless the page source is viewed; in a terminal they print exactly as listed.

🎯 Viva Questions

1. file_get_contents() vs fread() — when does each fit? file_get_contents() for one-shot reads of small files; fread() when a handle is needed for chunked reads, seeking or locking.
2. Why is an fgets() loop preferred for very large files? It reads one line per call inside while (!feof($handle)), so memory use stays constant regardless of file size.
3. What does the second argument of fread() specify? The maximum number of bytes to read from the pointer; passing filesize($path) there means "the whole file".
4. What does fopen() with mode "r" require and set up? The file must already exist; it opens read-only with the pointer at byte 0.
5. Why call fclose() when the script ends anyway? It promptly frees the handle and any lock; relying on script shutdown is sloppy in long-running or looping code.
6. Why wrap file content in htmlspecialchars() before echoing it on a web page? The file may contain markup; escaping turns it into visible text instead of executable HTML/JavaScript (XSS defence).

CO Mapping

CO1, CO2