Messages in this thread | | | From | Ustyugov Roman <> | Subject | Re: A pettiness question. | Date | Wed, 21 Sep 2005 12:00:05 +0400 |
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> Hi, All. > > I found there are use double operator ! continuously sometimes in > kernel. > e.g: > > static inline int is_page_cache_freeable(struct page *page) > { > return page_count(page) - !!PagePrivate(page) == 2; > } > > Who would like tell me why write like above? > > > Thanks in advanced. > > > Liyu
For example,
int test = 5; !test will be 0, !!test will be 1.
This give a enum of {0,1}. If test is not 0, !!test will give 1, otherwise 0.
Am I right? -- RomanU - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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