What’s the Difference Between is_readable and is_file in PHP? Which Scenarios Are They Best Suited For?

gitbox 2025-09-17

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Title: What’s the Difference Between is_readable and is_file in PHP? Which Scenarios Are They Best Suited For?

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Differences and Use Cases of is_readable and is_file in PHP
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In PHP development, it’s often necessary to check the state of a file or directory before deciding whether further operations are feasible. is_readable() and is_file() are two commonly used functions for this purpose, but their behavior and use cases differ.
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1. The is_readable() Function
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echo "is_readable(string $filename): bool';
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Use cases:
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echo "
Ensure the program has permission to read the file before attempting to access its contents.
Check whether an uploaded file can be safely read.
When working with configuration files, confirm readability before loading settings.
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2. The is_file() Function
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echo "is_file(string $filename): bool is used to check whether the given path points to a regular file (not a directory, symlink, etc.). If the path exists and is a file, it returns true; otherwise, it returns false.
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Example:
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echo '<br>
$filename = "example.txt";<br>
if (is_file($filename)) {<br>
echo "This is a file";<br>
} else {<br>
echo "This is not a file";<br>
}<br>
';
echo "
Use cases:
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echo "
Before performing file operations (such as delete or write), confirm that the target is a file and not a directory.
When iterating through directory contents, filter out regular files for processing.
Verify that an uploaded path is a file rather than a folder.
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3. Key Differences
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What they check: is_file() only checks if something is a regular file; is_readable() checks whether a file or directory is readable.
Permission check: is_readable() focuses on read permissions, while is_file() doesn’t care about permissions.
Return condition: is_file() returns true as long as it’s a regular file, even if unreadable; is_readable() requires the target to both exist and be readable.
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4. Summary
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echo "In short, is_file() is best for determining whether something is a file, while is_readable() is best for checking readability. In practice, you can combine them—for example, first use is_file() to confirm the path is a file, then is_readable() to ensure it’s accessible. This improves both robustness and security of your code.
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is_readable