Opening and Closing Files

To work with a file line by line, you open it, use it and close it. The three steps use fopen(), a read or write function, and fclose().

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<?php
$handle = fopen("notes.txt", "w");   // open for writing
fwrite($handle, "Hello file\n");
fclose($handle);                     // always close

echo file_get_contents("notes.txt");

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Hello file

fopen() returns a file handle (a resource, see Resources). You give that handle to the other file functions.

File modes

The second argument says what you want to do.

Add b (as in rb or wb) for binary files. It makes no difference on Linux, but on Windows it prevents line-ending conversion.

Check that opening worked

fopen() returns false and a warning when it fails: file missing, no permission or wrong path.

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<?php
$handle = @fopen("does-not-exist.txt", "r");

if ($handle === false) {
    echo "Could not open the file.";
} else {
    fclose($handle);
}

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Could not open the file.

The @ hides PHP’s warning here to keep the output short. In real code, avoid @, and handle the failure instead (for example log it and show a friendly message).

Why close the file

PHP closes open files when the script ends, but closing as soon as you are done:

• Frees the file for other processes.
• Makes sure buffered data is written.
• Keeps you from running out of open file handles in long scripts.

Safe pattern

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<?php
$handle = fopen("log.txt", "a");

if ($handle === false) {
    throw new RuntimeException("Cannot open log.txt");
}

try {
    fwrite($handle, "Started\n");
} finally {
    fclose($handle);   // runs even if something above fails
}

echo "Done";

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Done

finally guarantees fclose() runs. You will meet it in Error Handling.

When you do not need fopen

For small files, file_get_contents() and file_put_contents() are shorter. See file_get_contents() and file_put_contents(). Use fopen() when the file is large, or you need to read or write it in pieces.