うちに spot the difference


うちに has two rather confusingly different meanings.

One is in line with its never seen kanji form. Whilst. Do x whilst y.

Another means do x before y's situation changes.

The two are quite different as to when x should be done. Is there a way to
spot which is meant?




I don't think those meanings sound very different, but if you were to give
some examples we would be better able to address your question.

～うちに can be used in a number of (grammatical) situations, and in almost all of
those it can be understood in English1 as "while".

> 考えているうちに分からなくなった。  
>  _Kangaete iru uchi ni wakaranaku natta._  
>  (While thinking about it, I got lost.)

However, **when ～うちに follows a negative** it can be understood in English as
"before".

> 雨が降らないうちにテニスをしてきます。  
>  _Ame ga furanai uchi ni tenisu o shite kimasu._  
>  (I'll go and play tennis (and come back) before it rains.)

Additionally, when ～うちに is preceded by something for which the beginning and
ending is certain, ～間【あいだ】に can be substituted.

> 子供が学校に行っているうちに／間に本を読みます。  
>  _Kodomo ga gakkou ni itte iru uchi ni / aida ni hon o yomimasu._  
>  (I read books while my child is away at school.)

I hope this answers your question. If not, I am more than willing to expand
it.

* * *

Notes:  
1 Though as a matter of personal opinion, I don't believe this is the best way
to understand things in a foreign language.

* * *

References:  
Makino, Seiichi and Tsutsui, Michio. "A Dictionary of Basic Japanese Grammar".
Japan Times, 1994.

