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

We can use the `feof()` function to check if the 'end-of-file' (EOF) character has been found in a specified file.

The **`EOF` character** is a special character that marks the end of a file. In most cases, it identifies that the end of a file has been reached while reading data.

# Syntax
The following is the function prototype:

```php
 feof(file)
```
# Parameters and return value

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

- `file`: The file to be checked for the `EOF` character.

The function returns `TRUE` if the `EOF` character is found or an error occurs. Otherwise, the function returns `FALSE`.

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<?php 

# open a file
$file = fopen("Edpresso.txt", "r");

# using feof()
while (!feof($file))
{
    echo fgets($file); # read a line from the file
}

# close file
fclose($file);

?>

In the example above, we use `feof()` as our condition in a `while` loop.

The loop continues to read and display a line from the file until the `EOF` character is found. In such a case, the `feof()` function returns `TRUE`. The loop breaks because of the `!` operator, which flips the output to `FALSE`.

This allows us to read all the data from the file. 

What is the feof() function in PHP?

feof() in PHP checks for the end-of-file character in a specified file, returns TRUE if EOF or error occurs, and FALSE otherwise.