Hi:
I want to build an array that contain the pointer of some function in our program.
a simulated example is as below
//claim two function int x(void); int y (void); main() { int *(p)(void)[2]={x,y} }
When I compling, such error message appeared" error , an array of function" Dose keil support the array that contain the poiint of the function?
why I want to do this? There is an array while the first element is about the total amounts of the function to be execute, and the subsequent element indicate the corrponding function which will be execute. For example:
int array-A[3]={2,0,1}; //this mean that there is 2 functions(function_0 and function_1) will be executed.
Because of this, I want to build an extra array thant contain the pointer of the function such as below array-B={function_0_pointer,function_1_pointer};
According to the element in array-B, I will execute the corresponding function directly.
Is this idea can be supported?
Thanks for your replying!
Jason.Liu
Per, Andy, As you know I don't work with a C51. I'm curious: Is there sometimes a justification to use function pointer? Does it sometimes pay-off?
"I'm curious: Is there sometimes a justification to use function pointer? Does it sometimes pay-off?"
Sorry to butt in but I can give an answer to that.
Yes - But with the usual reason - When the situation requires it.
For example, a while ago I had the misfortune of being required to port an XML parser to an 8051 architecture. The source code relied quite heavily on function pointers, so I took the decision to use them and reduce the need for a lot of development time rather than rewrite the code in a lot of places to eliminate them.
The port was relatively straightforward, the code was reasonably close to the original and (thankfully) the customer was happy with the result :)
Are you asking in general if there is ever a justification to use function pointers, or just if it ever pays off in C51?
yes, of course there are many general cases where function pointers provide an ideal solution; some that spring immediately to mind are: Table-driven state machines; Table-driven user-interface menus; API call-backs.
Provided all the inplications are fully understood, and all the necessary precautions are taken, function pointers can be perfectly usable in C51.
But I think the OP's notion here that they give some inherent code size reduction is completely wrong?