====================================================================== hello, i got a problem with c programming, could anybody be kind enough telling me what goes wrong? i am writing a c program and using gcc in unix to compile it. well, i would like to use pointer to a function to replace if statements. I got them compiled perfectly, but when it is run, it gives an error :"Trace/Breakpoint Trap" and before an error:"Illegel Instruction". well, basically the program is spilt into several files: ~~~~~~~~~~~~~~~~~~~~~ algo.h : ThisStruct *best_fit(ThisStruct*, int); algo.c: define the above best_fit() function. main.c : ThisStruct* (*seek)(ThisStruct*, int); //declared in main function. and used it in main function as well: simulation(seek); in sim.c // define simulation function void simulation(ThisStruct* (*seek)(FreeList*, int)) ThisStruct *ptr; ThisStruct *node; int anInteger; ... ... ptr = seek(node, anInteger); // problem occurs ... ... } could anybody please tell me what the problem is? I did include all the header files properly, and the files got compiled perfectly (without any warning with gcc), but why when it is run, it gives the error memtioned above? thanks for reading this message and thanks a lot for any suggestions and recommendation. and well, please tell me as soon as possible if my question is not clear enough -i am very tired and sleepy now, but i need to get it done :( thanks again.

First of all, i hope you have linked all your odjects into a final executable. I see that you declare seek as ThisStruct* (*seek)(ThisStruct*, int); This is a pointer to a functions that takes two arguments, (ThisStruct*,int) and returns a ThisStruct*. ------------------ You also declare simulation as void simulation(ThisStruct* (*seek)(FreeList*, int)) This is a function that takes one argument and returns nothing. The argument is a pointer to a function that takes two arguments(FreeList*,int) and returns ThisStruct*. You've named that argument "seek". ----------------- So the first seek is a pointer to a function of type : ThisStruct*(ThisStruct*,int) And the second seek is a pointer to a function of type: ThisStruct*(FreeList*,int) I suppose ThisStruct and FreeList are not the same thing. In that case "node" is a ThisStruct* but it is passed to the "second seek".(The argument of the "simulation" function). This seek takes an argument FreeList* and not an ThisStruct*. So the problem is either in one of the following two lines --------------- void simulation(ThisStruct* (*seek)(FreeList*, int)) ThisStruct *node; --------------- Either the seek must take a ThisStruct* as an argument and not a FreeList*, or node must be a FreeList* and not a ThisStruct*. I believe the problem is at the declaration of simulation. I think it should be like that void simulation(ThisStruct* (*seek)(ThisStruct*, int)). NOT void simulation(ThisStruct* (*seek)(FreeList*, int)) ---------------- To avoid such probles try to define function pointer types using typedef. If you want to define a pointer to a function that takes an int and a char as arguments and returns a float you can do that this way: typedef float(*ICtoF)(int,char); Now you have defined the type ICtoF. Instances of that type are pointers to functions like the above. Eg code typedef float(*ICtoF)(int,char); float myfunc(int a,char c) // our function { float b = (float)(a + (int)c) + 0.5; return b; }; void main() { float a; int b = 7; char c = 'k'; ICtoF func; // Func is a pointer to a function like myfunc func = myfunc; a = func(b,c); }; S.A.Y.S. (Sam At Your Service) ;) :)