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Jean-Pierre Thank you for taking the time to provide such an excellent explanation. Message: 22 Date: Tue, 26 Nov 2002 12:42:55 +0100 From: Jean-Pierre Lavandier <> Subject: RE: Re: Arrays permitted in CodeWarrior for HC12? Bob Lewis Mgr. Process Computer Systems Tilbury Cement Ltd (604) 946-0411 work PO Box 950 (604) 946-2214 fax 7777 Ross Road (604) 727-1244 cell Delta, BC V4G 1B8 (888) 820-5852 pager (major cities) |
Arrays permitted in CodeWarrior for HC12?
Started by ●November 23, 2002
Reply by ●November 26, 20022002-11-26
Reply by ●November 27, 20022002-11-27
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Hi, My favourite array manupilation is the following... char *cal_ptr; cal_ptr = (char *)&(cal[x]); Where cal[] is an array of structures but could just as well be a elementry array of some sorts. ----- Original Message ----- From: "Daniel Friederich" <> To: <> Sent: Tuesday, November 26, 2002 2:40 AM Subject: RE: [68HC12] Re: Arrays permitted in CodeWarrior for HC12? > Actually, you can pass (almost) any C type as argument in C. The only thing special with arrays is that they are implicitly passed > by reference, and therefore it better to pass a pointer instead of an array to show this explicitly. The resulting code is > identical. > Passing large structs as argument is inefficient, especially in its stack usage, and should be avoided. > > As return value, you can use also (almost) any type except arrays. This makes sense as passing arrays by reference cannot be done > for arrays allocated on the stack. You can however still put the array inside of a struct and return it, but here the same remark as > for the passing of structs. It's slow and it needs a lot of stack. > > Anyway, here's a little example (which wastes a lot of stack space): > > typedef int intArray[2]; > typedef struct { intArray arr; } arrayInStruct; > > /* note: intArray foo(intArray arr); is illegal in C. No array return */ > arrayInStruct foo(intArray arr) { > arrayInStruct str; > arr[1]++; /* CAREFUL: changes globArray, as arr is passed by reference */ > str.arr[0]= arr[0]; > str.arr[1]= arr[1]; > return str; > } > > intArray globArray= {1,2}; > arrayInStruct globStruct= {{4,5}}; > void main(void) { > globStruct= foo(globArray); > } > > Bye > > Daniel > > > -----Original Message----- > > From: Erich Styger [mailto:] > > Sent: Tuesday, November 26, 2002 6:17 > > To: > > Subject: RE: [68HC12] Re: Arrays permitted in CodeWarrior for HC12? > > > > > > for C, you only can pass simple types (char, int, pointer, etc) as argument, > > but no arrays or structs (you have to use pointers). > > However, as return value, you can return a struct (struct-return). > > > > myStructType foo(void) { > > ... > > } > > > > Erich > > > > > -----Original Message----- > > > From: Andrei Chichak [mailto:] > > > Sent: Monday, November 25, 2002 5:03 PM > > > To: > > > Subject: Re: [68HC12] Re: Arrays permitted in CodeWarrior for HC12? > > > > > > > > > At 03:12 PM 11/23/2002 -0800, you wrote: > > > >You can pass/return a "struct" I believe, but it's not as efficient as > > > >passing/returning an address of an array (or whatever). > > > > > > > >GB > > > > > > GB! You should know better than that! C will only pass simple types, ints, > > > floats, pointers to complex types (structs, arrays), etc. You can appear to > > > pass in a struct, but you only pass a pointer to it. You can't pass out a > > > complex type, but you can pass out a pointer to one. DON'T pass out a > > > pointer to a local struct, it goes out of scope when the routine ends. > > > > > > Hey GB, are you doing Thanksgiving on Thursday or did you do it last month? > > > > > > AC > > > > > > > > > -------------------- > > > > > > > > > > > > ">http://docs.yahoo.com/info/terms/ > > > > > > > > > > > > -------------------- > > > > > > > > ">http://docs.yahoo.com/info/terms/ > > > > > -------------------- > > ">http://docs.yahoo.com/info/terms/ |
Reply by ●November 28, 20022002-11-28
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On 11:25 AM 11/25/2002 +0000, the keyboard of emmited: >a small example of what you are trying to do would be helpful. >Note that you cannot directly return an array with a C function: >you have to use a pointer instead (no return by value). >Maybe this is your problem? Yes, this was my problem. I tried: char * f(void); Now I changed to: void f(char*); -- Andres Rosado Email: ICQ: 66750646 Homepage: http://andres980.tripod.com/ If we all work together, we can totally disrupt the system. |
