xdiff_file_diff() makes unified diff of files file1 and file2 and stores result in file dest. context indicated how many lines of context you want to include in diff result. Set minimal to TRUE if you want to minimalize size of diff (can take a long time). Resulting file is human-readable.
注: This function doesn't work well with binary files. To make diff of binary files use xdiff_file_diff_binary().
如果成功则返回 TRUE,失败则返回 FALSE。
See also xdiff_string_diff().