fread() Function in PHP

The fread() function reads a specific number of bytes from an open file.

Syntax:

fread(resource $stream, int $length): string|false

• $stream: A file pointer (opened with fopen() or similar).
• $length: Number of bytes you want to read.
• Returns:
  • The read data as a string.
  • false if an error occurs.

Simple Example

Let's read 20 bytes from a text file:

<?php
// Open the file for reading
$handle = fopen("sample.txt", "r");

if ($handle) {
    // Read 20 bytes
    $content = fread($handle, 20);
    echo $content;

    // Close the file
    fclose($handle);
} else {
    echo "Error opening the file.";
}
?>

✅ Here:

• "sample.txt" is opened in read mode.
• fread() reads 20 bytes.
• Always fclose() after you're done!

Example: Read Full File

Usually, you don’t know the file size, so use filesize().

<?php
$handle = fopen("sample.txt", "r");

if ($handle) {
    $content = fread($handle, filesize("sample.txt"));
    echo $content;
    fclose($handle);
} else {
    echo "Error opening the file.";
}
?>

✅ Here:

• We first get the total size of the file using filesize("sample.txt").
• Then read the whole file in one go.

Important Points about fread()

• It reads binary-safe (can be used for images, PDFs, etc.).
• It does not automatically stop at end of line (\n) — it reads exact bytes.
• If the file pointer reaches EOF (End of File), it stops reading.

Real-world Example: Read an Image

<?php
$handle = fopen("photo.jpg", "rb"); // "rb" = read binary

if ($handle) {
    $imageData = fread($handle, filesize("photo.jpg"));
    fclose($handle);

    // Now $imageData contains binary data of the image
}
?>

This is useful when you want to send image data through API or store it in a database.

Quick Tip

If you only need to read a full file easily, PHP provides file_get_contents(), which is simpler:

$content = file_get_contents("sample.txt");

But if you want partial reading, large files, or streaming, fread() is better.