How can PHP developers ensure that file content is read into a variable without any additional output or formatting issues?

When reading file content into a variable in PHP, developers should use the `file_get_contents()` function to ensure that the content is read without any additional output or formatting issues. This function reads the entire file into a string variable, avoiding any unexpected output or formatting problems.

// Read file content into a variable without any additional output or formatting issues
$file_content = file_get_contents('file.txt');