MACROS - what can u do with them?

[beakie]

Can I use them to customise the header file???

I only want to include SomeStruct if I have defined MYARRAYSIZE

My Header File

#ifdef MYARRAYSIZE
struct SomeStruct {
int someArray[MYARRAYSIZE]
};
#endif 

Main.cpp (instance 1)

//nothing defined, struct won't be included and MYARRAYSIZE isnt required 

Main.cpp (instance 2)

#define MYARRAYSIZE 10
//MYARRAYSIZE is defined, struct is included and array is of size MYARRAYSIZE 

Is this proper?

[BlackSheep]

This seems dangerous, because you're including a header with the declaration of SomeStruct, but you can only use SomeStruct if MYARRAYSIZE is defined. Very counter-intuitive.

Either use something like a template to declare the size of someArray if you really need a compile time size for the array:

template<int T>
struct Array
{
    Array():size(T){}
    int& GetI(size_t index){return i[index];}
    const size_t GetSize(){return size;}
private:
    int i[T];
    size_t size;
};
//Note: very unsafe code. There is no bounds checking whatsoever for index. 

Or just use the vector class:
http://www.cplusplus.com/reference/stl/vector/

[R0mai]

@BlackSheep : there is already a class for this in the standard : std::array

http://www.cplusplus.com/reference/stl/array/