can not align when suffix of filename is ".c"

[lifang]

hello, i have following lines:

printf("a=aa");
printf("aaa=");

i want to align with "=", when suffix of filename is ".txt", or without suffix, i tryed to align with command vipga *=, got what i expected. but when suffix of filename is ".c", with command vipga *=, it does not work, if i delete the first quotation mark in lines, with following:

printf(a=aa");
printf(aaa=");

then, i try to align with command vipga *=, align ok.
i tried in vim 8.1.374 and nvim v0.3.0, the result is same.
any idea? thanks.

[Junegunn Choi]

See https://github.com/junegunn/vim-easy-align/blob/master/README.md#ignoring-delimiters-in-comments-or-strings