The **`filzesize()`** function is a built-in function in *PHP*.

The following is the function prototype:

```php
filesize(filename)
```

# Functionality

The `filesize()` function obtains the size of a file in bytes. The name of the file in question is passed as the input argument to the function.

# Parameters and return value

The `filesize()` function takes the following input parameters:

- `filename`: A string that represents the name of the file.

The function returns the size of the file in bytes in case of successful execution. The function returns `False` in case of failure.

# Code

As you know, the filesize() function returns the size of a file. 


<?php
    
echo "File size: ";
echo filesize("Edpresso.txt");
  
?>

Here, we create a text file by the name *Edpresso.txt*. 

This file is passed to the `filesize()` function and the size returned by the function is displayed.

What is the filesize() function in PHP?

Obtains file size in bytes: `filesize(filename)`, returns size or False on failure.