Identical to calling fopen(), fwrite(), and fclose() successively. The function returns the amount of bytes that were written to the file.
flags can take FILE_USE_INCLUDE_PATH and/or FILE_APPEND, however the FILE_USE_INCLUDE_PATH option should be used with caution.
Note: This function is binary-safe.
Tip: You can use a URL as a filename with this function if the fopen wrappers have been enabled. See fopen() for more details on how to specify the filename and Appendix L for a list of supported URL protocols.
See also fopen(), fwrite(), fclose(), and file_get_contents().