How can you read an entire document using PHP's file handling functions?

To read an entire document using PHP's file handling functions, you can use the `file_get_contents()` function to read the entire contents of a file into a string variable. This function reads the entire file into memory, so it may not be suitable for very large files. Alternatively, you can use the `fopen()`, `fread()`, and `fclose()` functions to read the file line by line.

// Using file_get_contents() to read the entire file into a string
$fileContents = file_get_contents('path/to/your/file.txt');
echo $fileContents;

// Using fopen(), fread(), and fclose() to read the file line by line
$handle = fopen('path/to/your/file.txt', 'r');
if ($handle) {
    while (($line = fgets($handle)) !== false) {
        echo $line;
    }
    fclose($handle);
}