More issues on Google Search

I've ranted previously about a lack of funtionality on Google Search. Since I've been replied with the sollution (thanks Bernardo!) which, unfortunately, is non-documented, I'm posting this wondering if there's any turn-around to the issue that someone might know...

I've just been asked about how to do something for the third time, and it's something I want to do some times and don't know how to either... How do you do a search for a specific file? If I search for file.c, Google will ignore the dot, and do the same search as in "file c"... How do you solve this issue?