Complicated declarations & definitions

As an aside, once you figure out how the C and C++ declaration syntax works you can create much more complicated items. For instance:

//: C03:ComplicatedDefinitions.cpp  

/* 1. */     void * (*(*fp1)(int))[10];  

/* 2. */     float (*(*fp2)(int,int,float))(int);  

/* 3. */     typedef double (*(*(*fp3)())[10])();              

fp3 a;  

/* 4. */     int (*(*f4())[10])();  int main() {} ///:~

Walk through each one and use the right-left guideline to figure it out. Number 1 says “fp1 is a pointer to a function that takes an integer argument and returns a pointer to an array of 10 void pointers.”

Number 2 says “fp2 is a pointer to a function that takes three arguments (int, int, and float) and returns a pointer to a function that takes an integer argument and returns a float.”

If you are creating a lot of complicated definitions, you might want to use a typedef. Number 3 shows how a typedef saves typing the complicated description every time. It says “An fp3 is a pointer to a function that takes no arguments and returns a pointer to an array of 10 pointers to functions that take no arguments and return doubles.” Then it says “a is one of these fp3 types.” typedef is generally useful for building complicated descriptions from simple ones.

Number 4 is a function declaration instead of a variable definition. It says “f4 is a function that returns a pointer to an array of 10 pointers to functions that return integers.”

You will rarely if ever need such co