PHP
Summary - File handling
Build a journal app with file_get_contents, file_put_contents and fopen.
Summary: the file handling toolkit
In this group you learned two approaches to file handling:
- One-shot: read the file as a string with
file_get_contents() and write a string with file_put_contents(). Ideal for short and simple tasks. - Handle-based: open with
fopen(), work with fwrite()/fread(), close with fclose(). Used when step-by-step reading or different modes are needed.
Now we will build a small journal app that combines both approaches.
Exercise Journal — one-shot approach
Write two entries to journal.txt. Write the first entry with file_put_contents() as 'Journal started' . PHP_EOL (resets the file). Append the second entry with the append flag as 'Learned PHP today.' . PHP_EOL. Then read the file with file_get_contents() and print it with echo.
Show example solution
Start with file_put_contents($file, 'Journal started' . PHP_EOL);. Then add file_put_contents($file, 'Learned PHP today.' . PHP_EOL, FILE_APPEND);. Finally echo file_get_contents($file);.
Example solution:
<?php
$file = __DIR__ . '/journal.txt';
// Write the first entry
file_put_contents($file, 'Journal started' . PHP_EOL);
// Append the second entry with FILE_APPEND
file_put_contents($file, 'Learned PHP today.' . PHP_EOL, FILE_APPEND);
// Read the file and print it
echo file_get_contents($file);
Recap of the handle-based flow
The handle-based approach has four steps:
- Open in the right mode (
'r', 'w', 'a') with fopen(). - Write with
fwrite() or read with fread(). - Reopen in a different mode if needed.
- Close with
fclose().
This flow gives flexibility through mode choice and prevents handles from staying open. Now we will build the same journal with handles.
Exercise Journal — handle-based approach
Open notes.txt with fopen() in 'w' mode and assign the handle to $wr. Use fwrite() to write 'First line' . PHP_EOL, then fwrite() again to write 'Second line' . PHP_EOL. Close with fclose($wr). Then open the file in 'r' mode, assign the handle to $rd, read 50 bytes with fread() into $content, close with fclose($rd) and print with echo $content.
Show example solution
Open with $wr = fopen($file, 'w');. Write fwrite($wr, 'First line' . PHP_EOL); fwrite($wr, 'Second line' . PHP_EOL); fclose($wr);. Then $rd = fopen($file, 'r'); $content = fread($rd, 50); fclose($rd); echo $content;.
Example solution:
<?php
$file = __DIR__ . '/notes.txt';
// Open in write mode
$wr = fopen($file, 'w');
// Write two lines and close
fwrite($wr, 'First line' . PHP_EOL);
fwrite($wr, 'Second line' . PHP_EOL);
fclose($wr);
// Open in read mode
$rd = fopen($file, 'r');
// Read 50 bytes, close and print
$content = fread($rd, 50);
fclose($rd);
echo $content;
Test yourself
-
Match functions to their jobs
- file_get_contents()
- Reads whole file as a string
- file_put_contents()
- Writes a string to a file
- fopen()
- Opens a file in a specific mode
- fclose()
- Closes the handle
-
You want to first write to a file and then read it back. What is the correct order?
- fopen('w') → fwrite → fclose → fopen('r') → fread → fclose
- fopen('w') → fread → fclose → fopen('r') → fwrite → fclose
- fopen('r') → fwrite → fread → fclose
- fopen('a') → fwrite → fread → fclose
Show answer
fopen('w') → fwrite → fclose → fopen('r') → fread → fclose — Correct. Open in write mode and close, then open in read mode and close.
Next lesson: The $_FILES superglobal
