I was reading a c++ code and i came across this problem and i don't know what it mean:
uint8 (*const flag_search)[SEARCH_RANGE]=
(uint8 (*)[SEARCH_RANGE])&_flag_search[MAX_MOTION][MAX_MOTION];
can someone explain it for me ?
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songyuanyao
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pooria
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You must clearly state what exactly you want to ask. – Tejendra Apr 22 '16 at 10:16
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Dear @Tejendra I want to know what it means : (uint8 (*)[SEARCH_RANGE]) – pooria Apr 22 '16 at 10:20
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1@pooria It's a pointer pointing to an array with element of type `uint8` and size of `SEARCH_RANGE`. – songyuanyao Apr 22 '16 at 10:21
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@songyuanyao tnx ! but what they gave me negative point ? :)) – pooria Apr 22 '16 at 10:51
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@pooria You might see the hint of the downvote button, your question is not pretty clear, and lack research effort. You could try to search on web firstly, if couldn't get the answer then ask here with specified question, such as which part of the code confused you, what did you think about it, etc. – songyuanyao Apr 22 '16 at 11:01
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Re: "confused" -- I agree completely. This is horrible code. – Pete Becker Apr 22 '16 at 11:09
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@songyuanyao tnq sir i will do my best next time ;) – pooria Apr 22 '16 at 11:17
1 Answers
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uint8 (*const flag_search)[SEARCH_RANGE]
flag_search is a const pointer pointing to an array, which contains SEARCH_RANGE elements with type uint8.
(uint8 (*)[SEARCH_RANGE])&_flag_search[MAX_MOTION][MAX_MOTION]
&_flag_search[MAX_MOTION][MAX_MOTION] will take the address of _flag_search[MAX_MOTION][MAX_MOTION], and cast it to uint8 (*)[SEARCH_RANGE], which is a non-const pointer pointing to an array, which contains SEARCH_RANGE elements with type uint8.
songyuanyao
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You should add that `MAX_MOTION` in this context is used as an array index, rather than array size. – user694733 Apr 22 '16 at 10:32
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so you tell me that there is some pointer that all refer to this array ? – pooria Apr 22 '16 at 10:35
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1@pooria Sorry I can't tell you that, it depends on relevant context. What I can tell you is only what it means. – songyuanyao Apr 22 '16 at 10:41