How do you check if a file exists in PHP?

The file_exists() function is the correct method to verify if a particular file exists within the filesystem. This built-in function accepts a single argument— the path to the file you want to check— and returns a boolean value: true if the file exists, and false if it does not. This is essential for handling file operations safely, as it allows developers to avoid runtime errors that could occur when attempting to access a file that isn't present.

The other options listed do not correspond to valid PHP functions. The file_check() and check_file() functions do not exist in PHP's standard library, and therefore cannot be used for file existence checks. The is_file() function, while it does check for the presence of a file, also verifies that the given path points to a regular file and not a directory, which makes it slightly different in usage compared to file_exists(). Consequently, using file_exists() is the most straightforward and appropriate approach when simply confirming the existence of a file.