Code Highlighting - How to highlight code in vim without specifying a file extension

Question

When using vim, when I specify a file suffix name with {code...}, it will be highlighted when writing the code. However, many times vim directly uses {code...} to specify the file name when saving. Is there any way to make vim recognize the first line of the file, for example, if php writes `&lt;?php`...

世界只因有你 · Answer

If you want to use a script to automatically detect the first line to determine the file type, I think it is not easy to implement.
But it can be used:

:set syntax=c

(php, java, etc.) Call the highlighted syntax of C (php, java, etc.) language in this file.
Or use

:set filetype=c

(Abbreviation se ft=c) Modify the file type.

曾经蜡笔没有小新 · Answer

This can still be achieved and can be solved using autocmd, :au BufRead * switchFileTypeManully()
In fact, when you do this, you also need to judge the file type based on the file characteristics, just like the suffix name.
Just like the PE file, the system will judge the file based on the file header and file attributes