operator []

[michy]

HI EXPERTS,
Question about overloading operator[]..
im wondering how im going to create a 2D object like 2D array....
in my main i want smth like this MyObj obj[5][5]
i just have no idea how to do it...so i just try a code below and heven't tested yet =DDD

code:

MyObj operator[](int a){   //i jus make the return value to the object itself?
 this->data = new int*[a];
 return *this;
}

thx for reading...

[Disch]

You don't.

You use the () operator instead:

//foo[1][2];  // bad
foo(1,2);  // good 

http://cplusplus.com/forum/articles/17108/#msg85595 <-- see the example "Array2D" class near the end of this post

[michy]

nice article..but maybe is my mistake that i didt mention that i just want to know the structure how actually the program read smth like x[1][1] or x(1)(1) i just wan to know the structure not how to use or do it...=)
Because i just learned operator () so in my program i just can do x(1) simple 1 but how if i wan try x(1)(1) ? Just curious about it....

[Disch]

but x(1)(1) is unintuitive and makes no sense. Just do x(1,1).

What you're asking is technically possible, but is very bad practice. It could be accomplished by making the first [] operator return an intermediate type (like a new class). The intermediate type would then also overload the [] operator to return the actual element you want to index.

But that potentially incurs some overhead, slowing your program down, and makes your code atrociously messy. So don't bother.