PHP fstat() Function: Usage and Examples

Use fstat() when you need to returns metadata for a file represented by an open stream in a PHP application. The examples below show the actual operation and its limitations.

What Is fstat() in PHP?

Returns metadata for a file represented by an open stream. The exact signature supported by your installation depends on its PHP version and enabled extensions.

Its syntax is:

fstat($stream): array|false

Parameters and return value: The parameter types, optional arguments, references, and return type are shown in the signature above. Optional parameters are marked with an ellipsis in this reference signature.

Example 1: Basic Usage

<?php

$stream = fopen("php://temp","w+"); fwrite($stream,"Hello"); echo fstat($stream)["size"]; fclose($stream);

Output:

5

Example 2: Different Input or Behavior

<?php

$stream = tmpfile(); fwrite($stream,"1234"); echo fstat($stream)["size"]; fclose($stream);

Output:

4

Practical Example: Applying the Function

<?php

$stream = tmpfile(); fwrite($stream,"invoice"); $metadata = fstat($stream); echo $metadata === false ? "Unavailable" : "Bytes: ".$metadata["size"]; fclose($stream);

Output:

Bytes: 7

Important Behavior and Edge Cases

Not all metadata fields are meaningful on every stream wrapper or platform.

Comparison With Related Functions

Common Beginner Mistakes

Key Takeaways

• Returns metadata for a file represented by an open stream.
• Not all metadata fields are meaningful on every stream wrapper or platform.
• stat() works on a pathname; fstat() inspects an already open stream.

Use fstat() for the specific operation demonstrated above. Check its prerequisites and handle failure conditions before using it with production data.