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arga
Joined: 09 Sep 2003
Posts: 22
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| Are pointers to functions supported in Ver. 3.173? |
 Posted: Sun Feb 15, 2004 11:06 pm |
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//sample basic code
int process1();
int process2();
int process3();
//create a table of pointers to functions
int (*pFunc)() processFunc[] = { process1, process2, process3 }; //compiler error message here: "Function definition different from previous definition"
main()
{
while(1)
{
//so..so..so
//just assume y is declared and assigned a value
x = processFunc[y]();
}
}
process1()
{
return(1);
}
process2()
{
return(2);
}
process3()
{
return(3);
} |
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Ttelmah
Guest
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| Re: Are pointers to functions supported in Ver. 3.173? |
| Posted: Mon Feb 16, 2004 5:00 am |
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| arga wrote: | //sample basic code
int process1();
int process2();
int process3();
//create a table of pointers to functions
int (*pFunc)() processFunc[] = { process1, process2, process3 }; //compiler error message here: "Function definition different from previous definition"
main()
{
while(1)
{
//so..so..so
//just assume y is declared and assigned a value
x = processFunc[y]();
}
}
process1()
{
return(1);
}
process2()
{
return(2);
}
process3()
{
return(3);
} |
The answer is 'yes, but'...
There are significant restrictions to what can/can't be done. Also the ability is there, but not fully 'supported' yet.
Your declaration of the pointer is incorrect to begin with. You are declaring 'pFunc' to be a pointer to a function, and then the declaration gets confused with the array.
The support, does not appear to spread to initialising as part of the declaration, unless the initialisation is to a constant value. Hence if you use #ORG to put a routine at a partucular location you can declare with this address, but not with a normal function name.
The support seems to only accept 'fixed' array indices, not variables.
So:
| Code: |
//sample basic code
int process1(void);
int process2(void);
int process3(void);
//create a table of pointers to functions
typedef int (*pFunc)(void);
pFunc processFunc[3];
//This works.
main()
{
int x,y;
processFunc[0]=process1;
processFunc[1]=process2;
processFunc[2]=process3;
//This works
while(1)
{
//so..so..so
//just assume y is declared and assigned a value
x = (*(processFunc[0]))();
//Note that your calling syntax was wrong.
//This works.
x = (*(processFunc[y]))();
//But this doesn't... :-(
}
}
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