AVR-Chat

Pass-by-reference is only available in C++.  In C you have to pass in a
pointer, and, for that, you use * as has been mentioned.

 void CalculateOffTime( uint8_t duration, offTimeStruct* eventOff )

then, eventOff->endMinute = ...

Martin Jay McKee

On Sat, Feb 2, 2013 at 2:22 PM, Charlie H <carlosh1@twcny.rr.com> wrote:

> **
>
>
> I agree with Clark on the pointer issue. The & should be * in the
> function declaration.
>
> Charlie
>
>
> On 2/2/2013 4:17 PM, englsprogeny1 wrote:
> >
> > I've updated the struct, thanks.
> >
> > I want to be able to update the values within the struct (depending on
> what 'instance' is passed into the function).
> >
> > This is why I am doing 'pass by reference' (by the address)
> >
> >
> > I get the following error:
> >
> > menu.c:1732: error: expected ';', ',' or ')' before '&' token
> >
> > This is referring to the prototype portion of the function definition.
> >
> >
> >
> > void CalculateOffTime(uint8_t duration, offTimeStruct &eventOff)
> >
> >
> >
> > Any more ideas?
> >
> >
> >
> > --- In AVR-Chat@yahoogroups.com, Charlie H wrote:
> >> It looks like you are expecting the address of the struct passed to your
> >> function but not using the address in the function. Try it this way:
> >>
> >> void CalculateOffTime(uint8_t duration, offTimeStruct eventOff)
> >> {
> >> ...
> >> }
> >>
> >>
> >> Also, I think the typedef is wrong. Try it this way:
> >>
> >> typedef struct
> >> {
> >> uint8_t endMinute;
> >> uint8_t endHour;
> >> } offTimeStruct;
> >>
> >>
> >> HTH,
> >> Charlie
> >>
> >>
> >> On 2/2/2013 2:51 PM, englsprogeny1 wrote:
> >>> Simple C question.. I guess that I am blowing! Maybe I didn't get
> enough sleep last night....
> >>>
> >>>
> >>> Using AVR Studio 4.0 with GCC
> >>>
> >>> 1. I create a type that is a struct
> >>> 2. I create multiple 'instances' of this type.
> >>>
> >>>
> >>> I get the following errors when I Build All:
> >>>
> >>> menu.c:1729: error: expected declaration specifiers or '...' before
> 'offTimeStruct'
> >>> menu.c:1742: error: 'eventOff' undeclared (first use in this function)
> >>>
> >>>
> >>>
> >>>
> >>> typedef struct offTimeStruct
> >>> {
> >>> uint8_t endMinute;
> >>> uint8_t endHour;
> >>> };
> >>>
> >>> offTimeStruct light1;
> >>> offTimeStruct rocket;
> >>>
> >>>
> >>>
> >>> //menu.c: Line 1729
> >>> void CalculateOffTime(uint8_t duration, offTimeStruct &eventOff)
> >>> {
> >>> //menu.c: Line 1742
> >>> eventOff.endMinute = 1;
> >>>
> >>> }
> >>>
> >>>
> >>>
> >>>
> >>> funtion call from Main()
> >>>
> >>>
> >>> CalculateOffTime(1, light1);
> >>>
> >>> Thanks for your ideas guys!
> >>>
> >>>
> >>>
> >>>
> >>>
> >>> ------------------------------------
> >>>
> >>> Yahoo! Groups Links
> >>>
> >>>
> >>>
> >>>
> >
> >
> >
> > ------------------------------------
> >
> > Yahoo! Groups Links
> >
> >
> >
> >
>
>  
>


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