Identical to file(), except that file_get_contents() returns the file in a string.
file_get_contents() is the preferred way to read the contents of a file into a string. It will use memory mapping techniques if supported by your OS to enhance performance.
注: 這個函數可安全的使用於二進位。
提示: 如果 fopen wrappers 已啟動，則可藉此函數把檔名當成URL使用。參考 fopen() 有更多關於如何指定檔名的細節和附錄 I支援URL協定的列表。
注: Context support was added with PHP 5.0.0.
See also: fgets(), file(), fread(), include(), and readfile().